His son, Stephen III., captured the town of Vidin or Bdin from the Bulgarians, and the district of Syrmia between the Save and the Danube. His brother, Ladislas, who succeeded him, abandoned Vidin on marrying the Bulgarian Tsar’s daughter. A third brother, Stephen IV. the Great, succeeded in 1237. With Stephen Uroš II. Milutin (succeeded 1275) Servia is almost at the height of her power. He conquered a large part of Macedonia, capturing the town of Serres, besieged Salonica in 1285, and invaded Albania. He added Bosnia, which had been under Hungarian vassalage, once more to Servia, by divorcing his first wife and marrying Elizabeth, the daughter of the King of Hungary, who gave him Bosnia as a dowry. His grandson, Stephen, who was called Dušan or the Strangler, because he had strangled his own father,[100] succeeded in 1331, and extended his power over the greater part of the Balkan peninsula. He conquered the rest of Macedonia and Albania, and reduced Bulgaria to a state of vassalage. In 1346 he had himself crowned “Tsar of the Serbs and Greeks.”[101] Bosnia, which corresponded to the modern region of that name, minus the eastern districts under Servia and the north-west corner, was ruled by a Banus who owed allegiance to Hungary. The first Banus, whose name is recorded in authentic documents, is Borić, who reigned from 1154 to 1163. During the next twenty years the country was under Byzantine suzerainty, represented at times by Greek governors, at others by native princes with Imperial diplomas. In 1180 the great Banus Kulin or Čulin came to the throne, shook off Byzantine authority, and ruled the country wisely and well for twenty-four years. He cultivated friendly relations with his neighbours, including Ragusa.[102] “The days of Čulin” became proverbial in later and less happy times to indicate a golden age. After Čulin’s death the country’s prosperity declined, but revived to some extent under Matthew Ninoslav (1232). After the death of his successor in 1254 Bosnia fell once more under Hungarian vassalage, and was divided into Bosnia proper (afterwards Bosnia-Mačva) under native vassal Bani, and the district of Usora and Soli ruled by Hungarian magnates. After a short period under the Croatian house of Šubić the native prince, Stephen Kotromanić, became Banus under Hungarian suzerainty, and reigned until 1353, when his nephew, Stephen Trvartko or Tvrtko,[103] succeeded him and crowned himself king.