On 26 September 1371, Vukašin was killed and his forces defeated in the Battle of Maritsa. About two months later, Tsar Uroš died. This formally made Marko the king of the Serbian land; however, Serbian noblemen, who had become effectively independent from the central authority, did not even consider to recognise him as their supreme ruler. Sometime after 1371, he became an Ottoman vassal; by 1377, significant portions of the territory he inherited from Vukašin were seized by other noblemen. King Marko, in reality, came to be a regional lord who ruled over a relatively small territory in western Macedonia. He funded the construction of the Monastery of Saint Demetrius near Skopje (better known as Marko's Monastery), which was completed in 1376. Later Marko became an Ottoman vassal and died on 17 May 1395, fighting against the Wallachians in the Battle of Rovine.