Since they were documented primarily by foreign authors whose knowledge of Central and East Europe geography was often vague, they were recorded by different names, which include Lendzanenoi, Lendzaninoi, Lz’njn, Lachy, Lyakhs, Landzaneh, Lendizi, Licicaviki and Litziki.[6][7] Gerard Labuda notes that the Rus' originally called a specific tribal group settled around the Vistula river as the Lendians and only later in the 11th and 12th century started to apply the name of the tribe to the entire populace of the "Piast realm" because of their common language.[citation needed] The most important factors contributing to their fate were linguistic and ethnic similarity, influence of Kievan Rus' and Orthodox Christianity, deportations to central Ukraine by Yaroslav I the Wise after 1031[24] and colonization of their lands by Ruthenians fleeing west during Mongol assaults on Ruthenia during reign of Danylo of Halych.[citation needed] Constantine VII reports that in the year 944 Lendians were tributaries to the Kievan Rus' and that their monoxylae sailed under prince Wlodzislav downstream to Kiev to take part in the naval expeditions against Byzantium.[33] Alexander Nazarenko considers that uncertainty of extant 10th-century descriptions of the upper Dniester and Bug River region makes it plausible to infer that the Lendians, White Croats and probably some other peoples shared this vast territory along the border of modern-day Ukraine and Poland.The early medieval sites near Dukla Pass, and villages Trzcinica and Przeczyca indicate that West Slavic material tradition started only at river Wisłoka, the right tributary of Upper Vistula.