The first written sources about Bac date bak to the year ad 535. When it was mentioned by the roman emperor Iustinian in a letter of his. In the year ad 873. Bac was a barbarian fortress. During the reign of the Arpad dynasty Bac was a king's town and the seat of the bishopric. In 1241. Bac was destroyed by the Mongolians. The fortress in Bac, which is now the oldest fortress in Vojvodina, was built by the king Charles Robert of the anjoy family during the period from 1338 to 1342. The fortress was built on a small island which originate from a meander of the river Mostonga. The fortress is one of the "Water Towns" becouse it was completely surrounded by water and the way to reach it was across drawbridges. After the battle of Mohach in 1529. the town and fortress wewe conquered the Turks, there are descriptions of the Bac fortess in the accounts of travels of Evly Cheleby which date from that period. Bac becomes a part of the Turkish administrative region of sezged. After the Rakotzy uprising (1702 - 1704) the fortress was burned, demolished and deserted and later never renovated again.