reign of Khan Presian (836–852). Numerous churches and monasteries were constructed after the Christianisation in 864. It remained within the borders of Bulgaria for 150 years until 1018, when the country was overrun by the Byzantines after half-century bitter struggle. According to De Administrando Imperio of the 10th century Byzantine Emperor Constantine VII, the Serbian-populated lands lay to the north-west of Kosovo and the region was Bulgarian. During the Uprising of Peter Delyan (1040–1041), Kosovo was briefly liberated and during the Uprising of Georgi Voiteh in 1072, Peter III was proclaimed Emperor of Bulgaria in Prizren from where the Bulgarian army marched to Skopje. In the beginning of the 13th century, Kosovo was reincorporated in the restored Bulgarian Empire but the Bulgarian control faded after the death of Emperor Ivan Asen II (1218–1241). Byzantine Period Around the 11th century, after the Byzantine Empire fully re-established itself, the region became part of the Byzantine Empire again and stayed under Byzantine rule until the 12th century. Serbian Period Kosovo was fully conquered by the Serbian state of Rascia in the late 12th and early 13th centuries, and was part of the Serbian Empire from 1346 to 1371. In 1389, the Battle of Kosovo occurred, which ended in a stalemate (both rulers, Murad I and Lazar Hrebeljanović, were killed). During the rule of the Nemanjić dynasty (c. 1160–1355), many Serbian Orthodox churches and monasteries were built throughout Serbian territory. From the mid-13th century to the end of the century, the Nemanjić rulers had their main residences in Kosovo. Large estates were given to the monasteries in Western Kosovo (Metohija). The most prominent churches in Kosovo – the Patriarchate at Peja, the church at Gračanica and the monastery at Visoki Dečani near Deçan – were all founded during this period. Kosovo was economically important, as the modern Kosovo capital Pristina was a major trading centre on routes leading to ports on the Adriatic Sea. Also, mining was an important industry in Novo Brdo and Janjevo which had its communities of émigré Saxon miners and Ragusan merchants. In 1450 the mines of Novo Brdo were producing about 6,000 kg of silver per year. The ethnic composition of Kosovo's population during this period included Serbs, Albanians, and Vlachs along with a token number of Greeks, Croats, Armenians, Saxons, and Bulgarians, according to Serbian monastic charters or chrysobulls. In the 14th century in two chrysobulls or decrees