Great Principality of Duklja

Duklja (Serbian Cyrillic: Дукља; Greek: Διόκλεια, romanized: Diokleia; Latin: Dioclea) was a medieval South Slavic state which roughly encompassed the territories of modern-day southeastern Montenegro, from the Bay of Kotor in the west to the Bojana river in the east, and to the sources of the Zeta and Morača rivers in the north. First mentioned in 10th– and 11th-century Byzantine chronicles, it was a vassal of the Bulgarian Empire between 997 and 1018, and then of the Byzantine Empire until it became independent in 1040 under Stefan Vojislav (fl. 1034–43) who rose up and managed to take over territories of the earlier Serbian Principality, founding the Vojislavljević dynasty. Between 1043 and 1080, under Mihailo Vojislavljević (r. 1050–81), and his son.