Çaka, Bey, active 11th century

Tzachas (Greek: Τζαχᾶς, romanized: Tzachás), also known as Chaka Bey (Turkish: Çaka Bey), was an 11th-century Seljuk Turkish military commander who ruled an independent state based in Smyrna. Originally in Byzantine service, he rebelled and seized Smyrna, much of the Aegean coastlands of Asia Minor and the islands lying off shore in 1088–91. At the peak of his power, he even declared himself Byzantine emperor, and sought to assault Constantinople in conjunction with the Pechenegs. In 1092, a Byzantine naval expedition under John Doukas inflicted a heavy defeat on him and retook Lesbos, while in the next year he was slain by his son-in-law Kilij Arslan I. Smyrna and the rest of Tzachas' former domain were recovered by the Byzantines a few years later, in c. 1097.