 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.Friar William described "Blakia" as "Assan's territory" south of the lower Danube, showing that he identified it with the northern regions of the Second Bulgarian Empire.