Greek colonies were established on the Pontus coast in 800 BC, and by the time of the conquests of Alexander the Great the local inhabitants were already heavily Hellenized. By the 4th century AD Greek had become the sole spoken language in the region, and it would remain so for a thousand years, first under the Byzantine Empire and then the Empire of Trebizond, a Byzantine successor state. In 1461 the Ottoman Empire conquered Pontus, but the remote mountainous region remained predominately Greek speaking for centuries more.