The territorial pretensions of the individual national movements and later political elites in the newly-established national states have been – approximately since 1830, but especially as of 1848 – the most frequent reason for the changes and rearrangements of the European national and internal administrative borders. Numerous European national movements that managed to assert their social and political power notably after the middle of the 19th century proclaimed their demands for the adaptation of the political and administrative borders to the national boundaries as their primary long-term programme goal. The social, cultural, and especially political strategies of the European national movements within the "non-national" state entities or the state policies of the nationalist elites in the newly-established states were therefore, in the 19th and 20th century, largely focused precisely on the attainment of this primary programme goal. This was also more or less characteristic for the Slovenian national movement, as the demand that "all Slovenians as well as their closest brothers should unite in a single nation, in order to create a united, single Slovenian Assembly" was clearly expressed already in 1848, in the first Slovenian national political programme.
It is absolutely certain that the social and political achievements of the European national movements and individual nationalist elites in the 19th and 20th century were by no means negligible. The specific unification, separatist, irredentist, or centralist national political programmes in fact contributed importantly to the dissolution of the existing empires and unification of what had previously been separated political-territorial units in the newly-formed national states. Furthermore, the new national(ist) elites in the newly-created national states were, in this period, quite successful in their efforts to abolish the "intra-state" social and regional differences as soon as possible, and effectively ensure that the class oppositions could be overcome. In this context the national movements attempted to fulfil their desire to gradually replace these sorts of differences and oppositions with the cultural unification of what had been very heterogeneous populations under the wing of national cultures. The circumstances were often such that the new national institutional frameworks had been created first, while the population was in fact nationalised subsequently (which, in turn, meant that modern national identity categories were adopted by the wider strata of the population).
The history of the creation and formation of the European national states in the 19th and 20th centuries confirms that numerous European national movements were quite successful in the realisation of their political programmes. In this regard we should obviously not overlook that precisely these attempts to implement the individual nationalist policies can be deemed as largely responsible for the unprecedented horrors that the European peoples have experienced in the past two hundred years. In the first half of the 20th century it turned out that the nationalist state policies and their intentional encouragement of the unexpected expansion of xenophobia and hatred between the nations contributed very significantly to the outbreak of two unprecedented military conflicts. In the nationalist imagery, such sacrifices as well as casualties of military conflicts, which the European national states had been involved in in the earlier as well as subsequent periods, were most often seen as expected and sensible. As such they were also worth remembering, at least judging from the frequency of commemorative gatherings and incidence of memorials that the national elites in the 19th and 20th century dedicated to the preservation of the memory of their respective nations' heroic acts throughout the European continent. Within the national context of remembrance, sacrificing oneself for one's nation and in its name has been understood as a contribution to the realisation of the thousand-year national aspirations and endeavours, and at the same time also as a contribution to overcoming the at least equally ancient national traumas.
In the 19th and 20th century, national traumas and aspirations would very frequently focus on the issue of constituting national territories. Consequently, it is not surprising that so much attention in the context of commemorative practices and national imagery is dedicated to the idea that the military and civilian lives should be sacrificed on the altar of their respective homelands, precisely in the name of fighting for the preservation of the national territories or with the intention of establishing the supposedly more natural national borders of the individual national communities. As it was, in the minds of zealous nationalists of the 19th and 20th centuries, national territories would often be understood as incomplete, i.e. as something that had yet to be finalised – most often on the account of the neighbouring political entities. This would supposedly once and for all make up for all the national injustices that had supposedly taken place in the past.
It seems that all the tragedy and absurdity of the millions of deaths, caused by the world wars as well as by all the other European conflicts between nations in the 19th and 20th century, can be considered in the context of the fact that not even the armies of the victorious states have ever secured the true national borders. It is obvious that national borders are, in their essence, neither natural nor objectively identifiable: not a single unbiased, indisputable, and irrefutable criterion exists that could definitely and objectively draw the line between two national communities on the map. Not even geographical obstacles or characteristics that in themselves stand out as the most obvious, apparent, and therefore believable criteria meet such requirements. Even if it seems, at the first glance, that geographical features can easily adopt the role of national demarcation lines as well, numerous examples of successful national movements that did not consider such barriers as insurmountable for the expansion of their nationally-determined visions speak in favour of the opposite. For this reason, it was already Ernest Renan (1823–1892) in his work What is a Nation? (Qu'est-ce qu'une nation?, 1882) that proposed as well as convincingly argued in favour of the standpoint that national borders did not depend on the geographical features.
It would be even harder to argue in favour of the thesis involving the existence of certain objectively specifiable cultural "markers", i.e. specific cultural characteristics, by means of which we could separate a certain population from another according to a definite national criterion. After all, the idea of hermetic and different mutually-exclusive national cultures and national cultural patterns can be immediately refuted, simply with a short and superficial excursion into the frontier-zone space on either side of any so-called national border. Precisely in such contemporary interstate or international regions we can easily note that the cultural and social phenomena are by no means conditioned solely with the adherence to a certain administrative-political unit or what we could, in the absence of a better expression, refer to as the "institutionally-supported national cultural framework". Quite the opposite: to a very significant extent, cultural patterns have never depended merely on the collection of the presupposed national determinants, as they have most often appeared either within wider supranational or narrower regional spaces, conditioned by very heterogeneous social and cultural forces. As Eric J. Wolf explained with a witty yet very extensively substantiated metaphor: nations, societies, or cultures simply do not possess any "qualities of internally homogeneous and externally distinctive bounded objects", which is why they do not spin off each other like billiard balls.
After all, national borders are hardly eternal, and they have especially not been with us always and forever. All of this is also true of the present-day Slovenian borders. It is certainly true that the national borders, envisioned in the past, could correspond to the older pre-existing administrative borders with a very long history. The southern border – today the border between Slovenia and Croatia – is an example of such an adaptation. The concept of the demarcation line between the "Slovenian" and "Croatian" nation that was formed in the 19th century largely corresponded to what had been a far older border of the medieval German state. Naturally, this by no means implies that the existing borders simply predestined the subsequent formation of national communities and consequently the creation of national borders. Quite the opposite: national borders, even Slovenian, could be drawn completely anew, ex nihilo, so to speak; which is what the history of nationalisms and nationalistic political endeavours in the 19th and 20th centuries actually addresses. Generally we could therefore conclude that the creation of national borders depends, from the historical perspective, on a combination of numerous factors – and chance is one of them, as well. At the same time the European history of the last two centuries also amply confirms the following: the border between two national communities or national states can only be established when the majority agrees with the line, drawn on the maps; or at least when this is agreed by the majority of those that possess the decision-making power or simply the political power in a given moment.
It seems that the history of establishing the Slovenian-Croatian border in the territory of the present-day Prekmurje region also underlines the importance of innovations, coincidences, and agreements for the definition and implementation of national borders. As it happened, in the 19th century, when this border was being defined, it was impossible to resort to the pre-existing administrative or political divisions and ascribe a new national significance to them. At the same time the Slovenian territory was impossible to clearly separate from the Croatian land, not even according to the linguistic criterion. Namely, the dialects, characteristic of this region – i.e. the today's Slovenian Prekmurje region dialects and the today's Croatian Kajkavian dialects from the Medjimurje region – have always been a part of the natural linguistic continuum. This means that both groups of dialects would even be difficult to separate today, if they were not already divided precisely by the strict territorial-political, administrative and/or national border. Naturally, in the 19th century such a border did not yet exist in the territory of what is today Prekmurje. Furthermore, it is difficult to imagine that a Slovenian-Croatian national border, envisioned in the 19th century, could also in fact assert itself as the administrative or territorial delimitation without the radical transformation of the European interstate relations at the end of World War I – namely, the transformation that stemmed from the introduction of a new principle, according to which the European interstate and international relations would be settled from then on: the nations' right to self-determination. Only in this context and on the basis of the revolutionary movement in Hungary could Slovenian diplomats as a part of the Yugoslav delegation at the peace negotiations in Paris even have the opportunity to argue for the standpoint that certain parts in the west of the Kingdom of Hungary should be treated as parts of the Slovenian national territory and therefore annexed to the Kingdom of Serbs, Croats and Slovenes.
To summarise: until as late as the dissolution of the Austro-Hungarian Empire at the end of World War I, the ideas of the Slovenian national activists about the national delimitations in the territory of the present-day Prekmurje region had nothing whatsoever to do with reality. The envisioned national border existed merely in the minds of a handful of Slovenians who lived and campaigned in the "Cisleithanian" territory, i.e. west of Prekmurje. The territory of what is today the Prekmurje region was, together with the territory of Medjimurje further to the south, a part of the Kingdom of Hungary for several centuries, since the Middle Ages until as late as the end of World War I.
The state border, established in such a manner on the river Mura, therefore very obviously separated the present-day Prekmurje from the other regions that the 19th-century Slovenian national activists considered to be Slovenian. Moreover, Slovenian national activists in "Cisleithania" started using the name "Prekmurje" for the supposedly Slovenian regions on the opposite bank of Mura relatively late, not until the second half of the 19th century. The name became fully recognised at the end of World War I, in the context of the efforts to annex this territory to the Kingdom of Serbs, Croats and Slovenes at the 1919 Paris Peace Conference. In the materials, prepared for these purposes by Matija Slavič (1877–1958) and Fran Kovačič (1867–1939), the name Prekmurje was used consistently, and therefore it also officially asserted itself as the name for this distinct geographical and historical territory. Otherwise the territory of the present-day Prekmurje "found itself in the same territorial unit: a diocese, although divided into two deanships – the Murska Sobota and Dolnja Lendava Deanship – separated by what had until then been the former Zagreb–Győr Diocese border, identical to the county border" as late as in 1777, after the establishment of the Diocese of Szombathely. Therefore the territory that is today the Prekmurje region had not existed as a unit in any sense until as late as the Marias Theresia's rearrangement of dioceses. Moreover, its southern part was especially strongly connected with Medjimurje across the river Mura (nowadays Croatia), as these regions had (until then) shared a common diocese and (until the very end) also administrative, i.e. county, framework. Before the merging within the borders of the same diocese (1777), the territory of the present day Prekmurje could be most easily defined descriptively, "as the frontier-zone space of the Kingdom of Hungary in the vicinity of the Holy Roman Empire, inhabited by the people who called themselves Sloveni and their language Slovenian".
Ever since the Middle Ages and until the dissolution of Austro-Hungary, the state, administrative, and for the large part of this period also the customs frontier followed the flow of the river Mura between Radgona in the north and the territory east of Ljutomer in the south, separating the today's Slovenian part of the former Austrian crown land of Styria from the territory of the today's Prekmurje. The significance of this border and the strictness of the frontier-zone regime have changed through the centuries – naturally, depending on the broader political circumstances on the one hand and the territorial changes in the immediate surroundings on the other hand. However, the border on the river Mura has certainly been never completely airtight for the frontier-zone population, even though these people lived in two different territorial-administrative units. The cross-border contacts strengthened significantly in the 19th century, when customs restrictions and controls on the Austrian-Hungarian border initially relaxed, only to be completely abolished for a while in 1850 and 1851. Consequently the contacts in this period were particularly lively and diverse, actively participated in by the communities that inhabited both banks of the river and its immediate vicinity.
However, even though the border by no means represented an insurmountable obstacle in the lives of the Habsburg subjects and simultaneously citizens of two different political entities on the left or the right bank of the river Mura in the 19th century, from the political or administrative viewpoint this border was nevertheless understood as a fact –a very tangible fact, at that, which asserted itself as virtually unchangeable in the 19th century due to what had by that time become a very long history of the extremely complicated relations between the Hungarian nobility and the Habsburg rulers. The river Mura represented the border, separating two administrative entities that may have shared a common ruler for a very long time, while they remained separate in the political and administrative sense.
How, then, was the concept that the today's Prekmurje should count as a specific Slovenian territory established in light of such circumstances – in the context of the borders that apparently had no parallels with the actually existing administrative-territorial delimitations in the long 19th century? When and why was the today's region of Prekmurje registered as Slovenian territory?
In the long 19th century, the idea of a distinct Slovenian territory – understood as the land inhabited by the members of the Slovenian nation – formed on the basis of the belief that all those subjects of the Austrian emperor who spoke Slovenian were also members of the Slovenian nation – in short, Slovenians. This sort of equalisation between the Slovenian language and Slovenian nation was, in turn, based on the completely new implications of the expressions "Slovenian language" or "Slovenians", as they had first been invented and disseminated by certain members of the intellectual circle that would gather regularly at the house of Sigismund Zois (1747–1819) in Ljubljana. These concepts were based on the so-called Carantanian Theory, initially formed by Anton Tomaž Linhart (1756–1795), as well as on the tradition of the Protestant literary endeavours in the Slovenian language, rediscovered and reinterpreted precisely at this time. Since the end of the first or the beginning of the second decade of the 19th century, what had in fact been a small circle of Inner Austrian intellectuals thus no longer used the expressions "Slovenian" and "Slovenian language" merely to denote the Slavic population and their language or to specifically refer to the Slavic people and their language in Styria or Carinthia, but rather, increasingly often, to define the Slavs and their language in the territory of Inner Austria, in the Kajkavian regions around Zagreb, and in certain western parts of Hungary.
These intellectual processes and mental transformations can be illustrated appropriately with the example of Valentin Vodnik's (1758–1819) literary opus. In Vodnik's essays, poems, and correspondence, precisely at this time the Carniolan provincial identification or identification as Carniolans started to be replaced by the ideas of a sort of a Slovenian community in the present-day meaning of the word. The latter is very tellingly illustrated by the corrections of Vodnik's Poem for my Fellow Countrymen (Péſma na moje rojáke), preserved as a part of his heritage. The poem was written towards the end of the 18th century within the exceedingly Carniolan context and way of thinking. However, in one of his first corrections of 1816, Vodnik already entitled it A Wakeup Call for my Fellow Countrymen (Dramílo mojih rojakov) and changed the first line of the first stanza – from "Carniolan! Your land is healthy" ("Krajnz! tvoja dežèla je sdrava") to "Slovenian, your land is healthy" ("Slovenz, tvoja zemla je zdrava"). However, this was not the first time that Carniolans transformed into Slovenians in this poem by Vodnik. The line "Slovenz, tvoja zemla je zdrava" or "Slovene! dein Land iſt geſegnet" had already appeared three years earlier in the reader, compiled in Graz by Vodnik's former student and correspondent at the time, Janez Nepomuk Primic (1785–1823).
The idea of this sort of a definition of the terms "Slovenian language" and "Slovenian", different in terms of contents, was based on the original classification of the Slavic peoples, constructed by Jernej Kopitar (1780–1844) on the basis of the previous historiographical findings of Anton Tomaž Linhart (1756–1795). Kopitar presented his classification for the first time in his renowned work entitled Grammar of the Slavic Language in Carniola, Carinthia, and Styria (Grammatik der Slavischen Sprache in Krain, Kärnten und Steyermark, 1808). The originality of the scheme that Kopitar would further upgrade and substantiate in the years and decades to come stemmed from the fact – to put it briefly – that by agreeing with certain Linhart's claims, Kopitar rejected the thesis of the famous Czech philologist Josef Dobrovski (1753–1829), who claimed that the so-called Windisch language in Carniola, Styria, and Carinthia should be considered Croatian, which he counted as one of the five major Slavic dialects (besides Russian, Polish, Illyrian, and Czech). Even though Kopitar agreed with the claim that the (Kajkavian) Croatian and the Inner Austrian Slovenian language were parts of the same Slavic dialect, he also – unlike Dobrovski – believed that on the basis of the historical primate of Carantania this language should be defined as Carantanian language, language of Carantanian Slavs, or, in German, as Windisch – i.e. Slovenian language. As it was, Carantanians were allegedly the oldest or longest-living Slavic people in this territory, and therefore they, as such, had the right to name the language after themselves rather than after Croats.
Consequently, immediately after the publication of his Grammar, Kopitar and his correspondents in fact started using the expression "Carantanian" and shortly afterwards the term "Slovenian language". In March 1811 Kopitar, in a letter to his patron Baron Žiga Zois (1747–1819), clearly defined the geographical dimensions of the envisioned separate Slavic language for the first time: "Therefore: 1. Slovenian in Carniola, Styria, and Carinthia; 2. so-called Croatian around Zagreb and so on; and 3. Slovenian (ſtari ſlovénski jesik) in the Hungarian counties near Lake Balaton; are three eusdem speciei variations", i.e., of the same kind. In the beginning of the 19th century, Kopitar thus defined in the modern sense, for the first time, who Slovenians were at all: those subjects of the Austrian Emperor that spoke Slovenian within the geographical borders specified for this language by Kopitar. In the following decades it turned out, of course, that all the speakers of the language constructed in such a manner did not also become the members of the modern Slovenian national community. This was especially true of the Kajkavian area around Zagreb, the part of the Civil Croatia that Matija Majar referred to in 1848 as "Banatsko". Nevertheless, the following holds true: in the middle of the 19th century, the equation between the geographical scope of Kopitar's Slovenian language on the one hand and the territorial dimensions of the Slovenian nation on the other hand asserted itself as the central ideological supposition of the nascent Slovenian national movement.
Even the earliest recorded statements about the integration of the present-day Prekmurje region into the wider Slovenian space were, precisely for this reason, made in the field of linguistic research. As France Kidrič established, this occurred for the first time in the writings of Jernej Kopitar, who "on 3 August 1809 in his letters to Zois and Zupan, but in the spring of 1810 also publicly, emphasised the adherence of the inhabitants of Prekmurje to the Slovenian nation". On the basis of Jernej Kopitar's works, Janez Nepomuk Primic (1785–1823), a professor at the Department of Slovenian Language at the lyceum in Graz, counted certain parts of the western Hungary to Slovenien in his 1814 work The New German-Slovenian Reader (Novi Nemſhko-Slovenſki Bukvar).
Outside the field of linguistic research and discussions, the present-day territory of Prekmurje was registered as a Slovenian territory in the 1840s, on the pages of Bleiweis's Kmetijske in rokodelske novice publication. In 1846, in the Novice newspaper, the Styrian priest Oroslav Caf (1814–1874) thus called upon the collectors of Slovenian words, urging them to send him their materials so that he could perfect his dictionary. On this occasion Caf wrote: "Slovenians! Do not forget or neglect the fact that your own authentic words are spoken in six countries among a variety of neighbours: in Hungary, Styria, Croatia, Carniola, Italy, and Carinthia; and that you are speaking the hallowed words, in which your great compatriot Kopitar chose to find the ancient Slavic language." In 1847 the author of the article entitled Slovenian Dictionary for Education and Amusement (Slovenski besédnik za poduk in kratek čas) in the Novice newspaper listed the dioceses where Slovenians allegedly lived, and wrote the following: "In Hungary – in the Vas and Zala Counties – 52,000 Slovenians live in 160 villages, in 18 Catholic and 4 Protestant parishes."
In the pre-March decades, Kopitar's construction of the separate Slovenian language, which also included the today's Prekmurje region in terms of territory, asserted itself among certain intellectuals who spoke and/or wrote in Slovenian; as did the conviction, based thereon, that the inhabitants of certain parts of western Hungary should count among Slovenians or among the speakers of Slovenian. With the onset of the revolutionary turmoil in 1848, very favourable political and social circumstances emerged as well, allowing for the politicisation of this kind of ideas and the public articulation of the nationally-defined political demands and expectations, thus paving the way for the formation of the Slovenian national movement.
The beginnings of the Slovenian national movement are related to the journalistic contributions and political endeavours of the Klagenfurt vicar Matija Majar (1809–1892). His writings should be understood as a sort of a foundation for the Slovenian nationalist ideology, as he is focusing precisely on the demand that all Slovenians, who had until then lived in the various Habsburg provinces, should come together in a single territorial and administrative unit and elect their political representatives themselves. In March or April 1848, Majar illustrated the latter even more clearly in the flier What do Slovenians Demand? (Kaj Slovenci terjamo?), which begins with the plea that "all Slovenians should unite in a single nation like brothers, and all of us should have a single Slovenian Provincial Assembly. There are 116,000 of us in Carinthia, 378,000 in Styria, 438,000 in Carniola, 217,000 in the Gorizia and Trieste regions, 22,000 in Banatsko, 60,000 in Hungary, and 230,000 in Istria. Thus we are divided between seven sides, all of us separated and paupers everywhere. Wherever we may raise our voices, there are not enough of us; whatever we may say can be easily ignored; but if we are united, there are almost a million and a half of us... Our word will have weight and will be heard everywhere; and all of us will benefit from this. We simply must have a single Assembly for the whole of Slovenia, joined by the estates and deputies from all the Slovenian lands with all the rights that they currently possess." Such nationally-defined political aspirations had not appeared before, in either the currently known pre-March or older sources. Even if Majar most probably based the formulation of his ideas extensively on the reports on the developments in the wider area of the German Confederation, his way of thinking and outlook on the social, territorial, and political organisation of the Habsburg lands was nevertheless completely original, nationally-influenced, and chronologically new. His assertion that the 60,000 Slovenians who lived "in Hungary" should be a part of this special Slovenian territorial-administrative unit as well is especially important for the research at hand.
Judging from the available sources, the incorporation of the present-day territory of Prekmurje or the local population into the concept of the Slovenian territory, Slovenian language, and Slovenian nation should be observed in the context of the formation of the Slovenian national thought, its expansion, as well as the subsequent emergence and assertion of the Slovenian national movement as of 1848. This means that, chronologically speaking, the idea of the Slovenian adherence or the Slovenian character of the today's territory of Prekmurje formed in the first half of the 19th century, very gradually and step by step: i.e., from the idea of the linguistic adherence of this area; through the cultivation of the Slovenian national thought; to the political development of this way of thinking in 1848, when Slovenians "in Hungary" were for the first time understood as a part of the single Slovenian national political body, which should, as such, be embodied in a separate political-territorial entity: Slovenia. However, in this regard the following should be underlined as well: in the pre-March period, the idea of the Slovenian adherence of the territory of what is today Prekmurje remained at the theoretical level throughout that time. Namely, the borders of the Slovenian territory in the modern national sense of the expression had never been clearly defined in the western parts of Hungary until the middle of the 19th century. Only after the outbreak of the March Revolution was the extent of the territory where Slovenians allegedly lived specified more precisely.
The first geographer to focus on the Slovenian geography and thus also the specification of the Slovenian border soon after the March events was, as it is very well known, Peter Kozler (1824–1879). His intention was to draw up "a map of the Slovenian land", which would, as he himself stated later, "show as precisely as possible how far and wide the Slovenian language is spoken". To a degree, Kozler was able to base his efforts on certain pre-March ethnographic depictions and maps, but he also acquired extensive new information either by himself or with the assistance of friends and acquaintances. As a curiosity it is worth mentioning that he had not intended to include the today's territory of Prekmurje in the map, as he had been unable to gather enough reliable information. He only acquired this information subsequently, and used it immediately for his article Slovenians in Hungary (Slovenci na Ogrskim), published in the Slovenija newspaper in 1849. The article was intended to contribute "to a greater recognisability of Slovenians living in Hungary, kindred to the Slovenians living in Styria and Illyria." In his article, Kozler defined the supposed scope of the Slovenian national settlement in Hungary and concluded that "the whole Hungarian – Slovenian territory includes around 170 towns and villages, located in 21 Catholic and 5 Protestant parishes". Kozler went on to list and describe these parishes, in the administrative-political sense belonging to the Zala or Vas Counties, and name them with their Slovenian names.
Furthermore, in 1849 everything was ready for the printing of the famous Kozler's map. Ultimately this did not occur that year, as the copperplate engraver whom Kozler had entrusted with the printing fled from Vienna and the copperplate vanished mysteriously. However, when the plate was finally located in 1851, Kozler organised the printing again, as well as prepared, as an annex to the map, "A Short Slovenian Geography and Overview of Political and Legal Division of the Illyrian Kingdom and Styrian Duchy with an Appendix of Slovenian and German Registry of Towns, Hamlets, Places etc." (Kratek slovenski zemljopis in pregled politične in pravosodne razdelitve Ilirskega kraljestva in Štajerskega vojvodstva s pridanim slovenskim in nemškim imenikom mest, tergov, krajev i.t.d.). Next year the Novice newspaper published an advert for the pre-ordering of the map, which allegedly "shows the borders of the Slovenian nation, its language, and its domain". However, the map had been confiscated and subject to many complications; and albeit dated 1853, it was not released until as late as 1861, i.e. eight years later.
As it has already been pointed out, the map was also accompanied by the Short Slovenian Geography (Kratek slovenski zemljopis), where Kozler argued, in writing, "how far the Slovenian word reaches". In the booklet that accompanied the map (Short Slovenian Geography), he defined the Slovenian-Croatian border in the territory of the today's Prekmurje as follows: »A dialect more similar to Slovenian rather than the Croatian language is spoken in the Croatian Littoral and by the Styrian border, in the Zagreb and Varaždin Counties nearly as far as Zagreb. However, the language here is changing gradually, and in the presence of so many local dialects the Croatian and its kindred Slovenian world cannot be separated very precisely. We can thus, for example, draw the border between these nations from the river Sava further towards Sotla, and the Styrian provincial borders as far as the rivers Drava and Mura.
From Mura and further to the north, the Slovenian language borders on Hungarian – i.e. from Dolnja Lendava through Hodož towards Szentgotthárd on the Rába river, and from there the national border runs towards the borders of the province of Styria and the border stream of Kučenica.”
This implies that at this time the initial Kopitar's idea of the scope of the Slovenian language in the south and east already digressed from the definition of the Slovenian-Croatian national borders. It is therefore obvious that in certain areas the idea of the linguistic border was not as relevant for the definition of the national territories as the old administrative borders. Moreover, in the case of Prekmurje, Kozler even had to resort to an analogy with the situation in Styria and promote the flow of the river Mura from the Styrian border as a sort of a dividing line between the nations, because, according to Kozler, "the language here is changing gradually, and in the presence of so many local dialects the Croatian and its kindred Slovenian world cannot be separated very precisely".
Apparently the territorial proximity and linguistic familiarity or permeability of the frontier-zone "Slovenian" and "Croatian" dialects had to be even far more obvious in the period before the introduction of the standard national languages in the administrative apparatus and in schools than it is today, and the originators of the national or ethnographic borders in the middle of the 19th century were clearly very confused by this fact. It seems that the question where the Slovenian language ended and Croatian began was not easy to solve, taking into account the dialects of the local population. We can also note this dilemma in the renowned Ethnography of the Austrian Monarchy (Ethnographie der österreichischen Monarchie, 1855–57), in which Czoernig – still following Kopitar's theory on the Slovenian adherence of the speakers of the Kajkavian dialect in the territory of Croatia – described the Slovenian-Croatian linguistic border as follows: »Die slovenisch-slovenokroatische Sprachgränze wird durch die Landesgränze zwischen Krain, Süd-Steiermark und Ungern einerseits, Kroatien anderseits bis Kott an der Mur gebildet. Doch zeigen manche Strecken, z.B. jene um Möttling in Krain, dann jene von Krapina bis gegen Varasdin, einen gegenseitigen sprachlichen Einfluss, so dass in ersterer kroatische und in letzerer häufiger als sonst slovenische Spracheigenheiten und Worte zu hören sind.«
However, judging from certain subsequent ethnographic descriptions from this period we can definitely conclude that the consciousness of the Slovenian adherence of the today's Prekmurje region nevertheless spread and strengthened considerably among the intellectuals and national-aware Slovenian Habsburg subjects from Cisleithania in the second half of the 19th century. Furthermore, it seems that such a viewpoint was also unconditionally received among the readers of the Slovenian literature and supporters of the Slovenian national movement at the beginning of the 20th century. For this reason, it is also not surprising that the question of the adherence of Prekmurje also surfaced at the end of World War I, when the new borders between the newly-formed states were being defined and drawn after the defeat and dissolution of Austro-Hungary. At the Paris Peace Conference, the Yugoslav delegation thus insisted on the standpoint that Prekmurje should be included in the Kingdom of Serbs, Croats and Slovenes as a part of the Slovenian national territory. Eventually this in fact happened, despite the opposition from a certain percentage of the local inhabitants. In the favourable political circumstances, the Army of the Kingdom of SHS first occupied Prekmurje on 12 August 1919, and with the Treaty of Trianon a new state border with Hungary was determined on 4 June 1920. Thus Prekmurje in fact became a part of the Kingdom of SHS. Even though different proposals, opinions, and standpoints would occasionally be voiced in the post-war time, in this period the demarcation along the river Mura – i.e. the delimitation as proposed by Peter Kozler in the middle of the 19th century – was conclusively implemented as the dividing line that separated the "Slovenian" from the "Croatian" in this area.
After the dissolution of Austro-Hungary and with the signing of the Treaty of Trianon, the administrative and subsequently also the state border that separated the Kingdom of Hungary into the Slovenian and Croatian part was finally implemented in the territory of the present-day Prekmurje, at the southern border with what is today the Croatian province of Međimurje. The dividing line between the two national communities, which had not formed as an idea until as late as the mid-19th century, thus became the political reality a few decades later.