From the 6th century BC, Greek, Roman, and Byzantine colonies were established on the north-eastern shore of the Black Sea, such as at Tyras, Olbia, and Chersonesus. These thrived into the 6th century AD. The Goths stayed in the area, but came under the sway of the Huns from the 370s. In the 7th century, the territory that is now eastern Ukraine was the centre of Old Great Bulgaria. At the end of the century, the majority of Bulgar tribes migrated in different directions, and the Khazars took over much of the land.