Exposed to nomadic incursions, Transylvania developed into an important border province of the Kingdom of Hungary. The Székelys—a community of free warriors—settled in central Transylvania around 1100 and moved to the easternmost regions around 1200. Colonists from the Holy Roman Empire—the Transylvanian Saxons' ancestors—came to the province in the 1150s. A high-ranking royal official, styled voivode, ruled the Transylvanian counties from the 1170s, but the Székely and Saxon seats (or districts) were not subject to the voivodes' authority. Royal charters wrote of the "Vlachs' land" in southern Transylvania in the early 13th century, indicating the existence of autonomous Romanian communities. Papal correspondence mentions the activities of Orthodox prelates among the Romanians in Muntenia in the 1230s. Also in the 13th century, during one of its greatest periods of expansion, the Republic of Genoa started establishing many colonies and commercial and military ports on the Black Sea, in the current territory of Romania. The largest Genoese colonies in present-day Romania were Calafat (still known as such), Constanța (Costanza), Galați (Caladda), Giurgiu (San Giorgio), Licostomo and Vicina (unknown modern location). These would last until the 15th century.