 Between the 1st and 7th centuries AD, the south came intermittently under the control of the Roman and then the Byzantine Empires.Due to its strategic location on a route between Asia and Europe, the territory of modern Moldova experienced many invasions in late antiquity and the early Middle Ages, including by Goths, Huns, Avars, Bulgarians, Magyars, Pechenegs, Cumans, Mongols and Tatars.Friar William of Rubruck, who visited the court of the Great Khan in 1254, listed "the Blac", or Vlachs, among the peoples who paid tribute to the Mongols, but the extent of the Vlachs' territory remains uncertain.