 Complete the following phrase:  By early 1290s Serbia expanded towards the vicinity of Vidin. Threatened by Serbian expansion, Shishman failed to repel the brothers forces, and accepted Serbian suzerainty. In practice, Shishman continued to be largely independent and dealt mainly with Bulgaria. Serbian suzerainty lasted until Serbian king Stefan Milutin s death, in 1321. As Milutin left no testament, after his death, in Serbia occurred a period of civil war with Stefan Dečanski, Stefan Konstantin and Stefan Vladislav II fighting for power. Shishman took advantage of this situation, set free from Serbian rule, and returned to the Bulgarian sphere. In 1323 Shishman was chosen to be the Bulgarian tsar. Shishman made an anti-Serbian treaty with the Byzantines, however, after Serbian victory over Bulgarians in the 