 His report is buttressed by the foundation charter of the Archdiocese of Prague (1086), which traces the eastern border of the archdiocese, as established in 973, along the Bug and Styr (or Stryi) rivers.Abraham ben Jacob, who travelled in Eastern Europe in 965, remarks that Boleslaus II of Bohemia ruled the country "stretching from the city of Prague to the city of Krakow".At one point around 960, the region seems to have been taken over by Mieszko I of Poland.