 Under the Byzantine emperor Heraclius (610–641), Lydia became part of Anatolikon, one of the original "themata", and later of Thrakesion.Although the Seljuk Turks conquered most of the rest of Anatolia, forming the Sultanate of Ikonion (Konya), Lydia remained part of the Byzantine Empire.While the Venetians occupied Constantinople and Greece as a result of the Fourth Crusade, Lydia continued as a part of the Byzantine rump state called the Nicene Empire based at Nicaea until 1261.