Hungary is a landlocked country in Central Europe. Spanning much of the Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and Slovenia to the southwest, and Austria to the west. Hungary lies within the drainage basin of the Danube River and is dominated by great lowland plains. It has a population of 9.6 million, consisting mostly of ethnic Hungarians (Magyars) and a significant Romani minority. Hungarian is the official language, and among the few in Europe outside the Indo-European family. Budapest is the country's capital and largest city, and the dominant cultural and economic centre. Prior to the foundation of the Hungarian state, various peoples settled in the territory of present-day Hungary, including the Celts, Romans, Huns, Germanic peoples, Avars and Slavs. Hungarian statehood is traced to the Principality of Hungary, which was established in the late ninth century by Álmos and his son Árpád through the conquest of the Carpathian Basin. King Stephen I ascended the throne in 1000 and converted his realm to a Christian kingdom. The medieval Kingdom of Hungary was a European power, reaching its height in the Late Middle Ages.