Byzantine emperor Andronikos II Palaiologos tried to form an alliance with the Ilkhanid Mongols against the Ottoman threat.

The recent defeat at Marj al-Saffar and the rapid decentralization of Mongol domains in Anatolia and the Middle East made him decline.

According to Theodore Spandounes, "Dimbos" (in Greek) or "Dinboz" (deriving from din bozmak, "change of faith") was the first Byzantine town to fall to the Ottomans.

In the spring of 1303, the Byzantine army gathered in Bursa and advanced to Yenişehir, the capital of the Ottoman Turks which was north east of the city.

[4][5] As the Byzantines started to tire, the cavalry under Orhan forced them into an organised retreat which achieved the Ottoman victory.