After Ottoman expansion into Byzantine territories in the east in the first half of the 14th century, the internally divided Bulgarian Empire and the short-lived and crumbling Serbian Empire stood next. In 1371, the Ottomans defeated a large Serbian army at the Battle of Maritsa, and in 1389 defeated the Serbian army at the Battle of Kosovo. By now, Serbian and Bulgarian rulers became Ottoman vassals, the southern Serbian provinces and Bulgaria holding out until annexation in the 1390s. The Ottomans conquered Constantinople (1453), Greece (1453–60), the Serbian Despotate (1459) and Bosnia (1463). Much of the Balkans was under Ottoman rule throughout the early modern period. Ottoman rule lasted from the 14th into the early 20th century in some territories. Ottoman society was multi-ethnic and multi-religious, and confessional groups were divided according to the "millet" system, in which Orthodox Christians (Greeks, Bulgarians, Serbs, etc.) constituted the Rum Millet. In Islamic jurisprudence, the Christians had "dhimmi" status, which entailed certain taxes and lesser rights. Through Islamization, communities of Slavic Muslims emerged, which survive until today in Bosnia, south Serbia, North Macedonia, and Bulgaria.