Chaka (from Turk. çaka[n], “axe”), known as Tzachas in Greek sources, was the Turkish emir of Smyrna (mod. Izmir, Turkey) and its surrounding area at the time of the First Crusade (1096-1099). His maritime principality came to include most of the Ionian littoral and several eastern Aegean islands, and his aspirations included the Byzantine throne itself.
While a hostage in the court of the Byzantine emperor Nikephoros III Botaneiates, Chaka received the high title of protonovelissimos and possibly baptism, although later in his career he definitely reverted to Islam. Around 1081, having obtained prominence in Byzantium and organized a fleet, he gained control of Smyrna and the surrounding areas of Kla- zomenai and Phokaia, and razed Adramyttion to the ground. For almost a quarter of a century he posed a serious threat to Emperor Alexios I Komnenos. With the help of a Christian Smyrniote, he created a powerful fleet and a piratical army of 8,000 troops, with which he raided (and in some cases, took control of) several Aegean islands in 1088/1089 and 1092/1093; his combined attack with the Pechenegs against Constantinople (1090-1091) was the only case during the Saljûq period when the Turks laid siege to the Byzantine capital.
Even after being driven out of Smyrna by the Byzantines (1096-1098/1099), Chaka was far from being neutralized. Alexios I eventually succeeded in convincing Chaka’s son-in- law Qilij Arslān I, sultan of Rûm, that his domains were Chaka’s real target, which caused the sultan to lure the emir to a banquet in Abydos, where the sultan himself stabbed Chaka to death.