Question: What southern part of the Kingdom of Slavonia straddled the borderland of the Habsburg Monarchy?

full_context: Document 1: Varaždin County (former): Varaždin County (Croatian: "Varaždinska županija" ; Hungarian: "Varasd vármegye" ) was an administrative subdivision ("županija") of the Kingdom of Croatia-Slavonia. Croatia-Slavonia was an autonomous kingdom within the Lands of the Crown of Saint Stephen (Transleithania), the Hungarian part of the dual Austro-Hungarian Empire. Its territory is now in northern Croatia. The capital of the county was Varaždin (Croatian, in Hungarian: "Varasd").
Document 2: Military Frontier: The Military Frontier was a province straddling the southern borderland of the Habsburg Monarchy and later the Austrian and Austro-Hungarian Empire. It acted as the "cordon sanitaire" against incursions from the Ottoman Empire.
Document 3: Moravia: Moravia ( ; Czech: "Morava" ; German:    ; Polish: "Morawy" ; Latin: "Moravia" ) is a historical country in the Czech Republic (forming its eastern part) and one of the historical Czech lands, together with Bohemia and Czech Silesia. The medieval and early modern Margraviate of Moravia was a crown land of the Lands of the Bohemian Crown (from 1348 to 1918), an imperial state of the Holy Roman Empire (1004 to 1806), later a crown land of the Austrian Empire (1804 to 1867) and briefly also one of 17 former crown lands of the Cisleithanian part of the Austro-Hungarian Empire from 1867 to 1918. During the early 20th century, Moravia was one of the five lands of Czechoslovakia from 1918 to 1928; it was then merged with Czech Silesia, and eventually dissolved by abolition of the land system in 1949.
Document 4: Austria-Hungary: Austria-Hungary, often referred to as the Austro-Hungarian Empire or the Dual Monarchy in English-language sources, was a constitutional union of the Austrian Empire (the Kingdoms and Lands Represented in the Imperial Council, or "Cisleithania") and the Kingdom of Hungary (Lands of the Crown of Saint Stephen or "Transleithania") that existed from 1867 to 1918, when it collapsed as a result of defeat in World War I. The union was a result of the Austro-Hungarian Compromise of 1867 and came into existence on 30 March 1867. Austria-Hungary consisted of two monarchies (Austria and Hungary), and one autonomous region: the Kingdom of Croatia-Slavonia under the Hungarian crown, which negotiated the Croatian–Hungarian Settlement ("Nagodba") in 1868. It was ruled by the House of Habsburg, and constituted the last phase in the constitutional evolution of the Habsburg Monarchy. Following the 1867 reforms, the Austrian and the Hungarian states were co-equal. Foreign affairs and the military came under joint oversight, but all other governmental faculties were divided between respective states.
Document 5: Economy of the Habsburg Monarchy: With the abolition of serfdom in the 18th century, the Habsburg Monarchy, with the major industrial, mining areas and forestry of regions Moravia and Bohemia leading the way, began to experience unprecedented economic growth. Beginning in 1841 per capita annual growth in the Habsburg monarchy approached 3.6 percent, a number rivaling that of neighboring Germany. While this growth was rapid and astonishing, it was not sustained.
Document 6: Kingdom of Slavonia: The Kingdom of Slavonia (Croatian: "Kraljevina Slavonija" ; German: "Königreich Slawonien" ; Latin: "Regnum Sclavoniae" ; Hungarian: "Szlavón Királyság" ) was a province of the Habsburg Monarchy and the Austrian Empire that existed from 1699 to 1868. The province included northern parts of present-day regions of Slavonia (today in Croatia) and Syrmia (today in Serbia and Croatia). The southern parts of these regions were part of the Slavonian Military Frontier, which was a section of the Military Frontier.
Document 7: Ottoman–Habsburg wars: The Ottoman–Habsburg wars were fought from the 16th through the 18th centuries between the Ottoman Empire and the Habsburg (later Austrian) Empire, which was at times supported by the Holy Roman Empire, Kingdom of Hungary and Habsburg Spain. The wars were dominated by land campaigns in Hungary (including Transylvania and Vojvodina), Croatia and Central Serbia.
Document 8: Habsburg Monarchy: The Habsburg Monarchy (German: "Habsburgermonarchie" ) or Empire, is an unofficial appellation among historians for the countries and provinces that were ruled by the between 1521 and 1780 and then by the successor branch of Habsburg-Lorraine until 1918. The Monarchy was a composite state composed of territories within and outside the Holy Roman Empire, united only in the person of the monarch. The dynastic capital was Vienna, except from 1583 to 1611, when it was moved to Prague. From 1804 to 1867 the Habsburg Monarchy was formally unified as the Austrian Empire, and from 1867 to 1918 as the Austro-Hungarian Empire.
Document 9: Duchy of Carniola: The Duchy of Carniola (Slovene: "Vojvodina Kranjska" , German: "Herzogtum Krain" ) was a State of the Holy Roman Empire, established under Habsburg rule on the territory of the former East Frankish March of Carniola in 1364. A hereditary land of the Habsburg Monarchy, it became a constituent land of the Austrian Empire in 1804 and part of the Kingdom of Illyria until 1849. A separate crown land from 1849, it was incorporated into the Cisleithanian territories of Austria-Hungary from 1867 until the state's dissolution in 1918. Its capital was Ljubljana.
Document 10: Kingdom of Croatia-Slavonia: The Kingdom of Croatia-Slavonia (Croatian: "Kraljevina Hrvatska i Slavonija" ; Hungarian: "Horvát-Szlavón Királyság" ; German: "Königreich Kroatien und Slawonien" ) was a nominally autonomous kingdom within the Austro-Hungarian Empire, created in 1868 by merging the kingdoms of Croatia and Slavonia following the Croatian–Hungarian Settlement. It was associated with the Hungarian Kingdom within the dual Austro-Hungarian state, being within the Lands of the Crown of St. Stephen or Transleithania. The kingdom was ruled by the Habsburg Emperor-King of Austria-Hungary ("Kaiser und König") under his title as "King of Croatia and Slavonia". The King's appointed steward was the Ban of Croatia and Slavonia. Although it was under the suzerainty of the Crown of Saint Stephen, the Kingdom of Croatia and Slavonia kept a significant level of self-rule.
Document 11: Slavonian Military Frontier: The Slavonian Military Frontier (Croatian: "Slavonska vojna krajina" or "Slavonska vojna granica ") was a district of the Military Frontier, a territory in the Habsburg Monarchy, first during the period of the Austrian Empire and then during the Austro-Hungarian Monarchy. It was formed out of territories the Habsburgs conquered from the Ottoman Empire and included southern parts of Slavonia and Syrmia; today the area it covered is mostly in eastern Croatia, with its easternmost parts in northern Serbia (mostly in Vojvodina region).
Document 12: Varaždin Generalate: The Varaždin Generalate (German: "Warasdiner Generalat" , Croatian: "Varaždinski generalat" ), also known as the "Windische Grenze" ("Wendian/Wendish [Slavic] Border") in German, was a Habsburg Monarchy Military Frontier province centred in Warasdin (Varaždin), Kingdom of Croatia within Habsburg Monarchy, that existed between 1531 and the 18th century.
Document 13: Kingdom of Croatia (Habsburg): The Kingdom of Croatia (Croatian: "Kraljevina Hrvatska"; Latin: "Regnum Croatiae" Hungarian: "Horvát Királyság" German: "Königreich Kroatien" ) was an administrative division that existed between 1527 and 1868 within the Habsburg Monarchy (also known between 1804 and 1867 as the Austrian Empire). The Kingdom was a part of the Lands of the Crown of St. Stephen, but was subject to direct Imperial Austrian rule for significant periods of time, including its final years. Its capital was Zagreb.
Document 14: Roman military frontiers and fortifications: Roman military borders and fortifications were part of a grand strategy of territorial defense in the Roman Empire, although this is a matter of debate. By the early 2nd century, the Roman Empire had reached the peak of its territorial expansion and rather than constantly expanding their borders as earlier in the Empire and Republic, the Romans solidified their position by fortifying their strategic position with a series of fortifications and established lines of defense. Historian Adrian Goldsworthy argues that the Romans had reached the natural limits which their military traditions afforded them conquest over and that beyond the borders of the early-to-mid Empire lay peoples whose military traditions made them militarily unconquerable, despite many Roman battle victories. In particular, Goldsworthy argues that the cavalry-based warfare of the Parthians, Sarmatians and Persians presented a major challenge to the expansion of Rome's infantry-based armies.
Document 15: History of Transylvania: Transylvania is a historical region in central and northwestern Romania. It was part of the Dacian Kingdom (1st–2nd centuries CE), Roman Dacia (2nd–3rd centuries), the Hunnic Empire (4th–5th centuries), the Kingdom of the Gepids (5th–6th centuries), the Avar Khaganate (6th–9th centuries) and the 9th century First Bulgarian Empire. During the late 9th century, western Transylvania was reached by the Hungarian conquerors and later it became part of the Kingdom of Hungary, formed in 1000. After the Battle of Mohács in 1526 it belonged to the Eastern Hungarian Kingdom, from which the Principality of Transylvania emerged. During most of the 16th and 17th centuries, the principality was a vassal state of the Ottoman Empire; however, the principality had dual suzerainty (Ottoman and Habsburg). In 1690, the Habsburgs gained possession of Transylvania through the Hungarian crown. After 1711 Habsburg control of Transylvania was consolidated, and Transylvanian princes were replaced with Habsburg imperial governors. After the Austro-Hungarian Compromise of 1867, the separate status of Transylvania ceased; it was incorporated into the Kingdom of Hungary (Transleithania) as part of the Austrian-Hungarian Empire. After World War I, Transylvania became part of Romania. In 1940 Northern Transylvania reverted to Hungary as a result of the Second Vienna Award, but it was reclaimed by Romania after the end of World War II.
ground_truth: The Military Frontier