The Counts of Celje or the Counts of Cilli were the most influential late medieval noble dynasty on the territory of present-day Slovenia. Risen as vassals of the Habsburg dukes of Styria in the early 14th century, they ruled the County of Cilli as immediate counts (Reichsgrafen) from 1341. They soon acquired a large number of feudal possessions also in today's Croatia and Bosnia. They rose to Princes of the Holy Roman Empire in 1436. The dynasty reached its peak with Ulrich II of Cilli, but with his death in 1456 they also died out, and after a war of succession, the Habsburgs inherited their domains.

Slovenia officially the Republic of Slovenia, is a country in southern Central Europe. Slovenia is bordered by Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the south and southeast, and a short coastline within the Adriatic Sea to the southwest. Slovenia is mostly mountainous and forested, covers 20,271 square kilometres (7,827 sq mi), and has a population of approximately 2.1 million. Slovene, a South Slavic language, is the official language. Slovenia has a predominantly temperate continental climate, with the exception of the Slovene Littoral and the Julian Alps. A sub-mediterranean climate reaches to the northern extensions of the Dinaric Alps that traverse the country in a northwest–southeast direction. The Julian Alps in the northwest have an alpine climate. Toward the northeastern Pannonian Basin, a continental climate is more pronounced. Ljubljana, the capital and largest city of Slovenia, is geographically situated near the centre of the country.