Nestor described how many East Slavic tribes of ""...the Polyanians, the Derevlians, the Severians, the Radimichians, and the Croats lived at peace"". In 904–907, ""Leaving Igor (914–945) in Kiev, Oleg (879–912) attacked the Greeks. He took with him a multitude of Varangians, Slavs, Chuds, Krivichians, Merians, Polyanians, Severians, Derevlians, Radimichians, Croats, Dulebians, and Tivercians, who are pagans. All these tribes are known as Great Scythia by the Greeks. With this entire force, Oleg sallied forth by horse and by ship, and the number of his vessels was two thousand"". The list indicates that the closest tribal neighbours were Dulebes-Volhynians, The fact no Lechitic tribe was part of Oleg's conquest it is more probable that those Croats were located on river Dniester rather than Vistula. After Vladimir the Great (980–1015) conquered several Slavic tribes and cities to the West, in 992 he ""attacked the Croats. When he had returned from the Croatian War, the Pechenegs arrived on the opposite side of the Dnieper"". Since then those Croats became part of Kievan Rus and are not mentioned anymore in that territory. It seems that Croatian tribes who lived in the area of Bukovina and Galicia were conquered because inhibited Kievan Rus free access to the Vistula valley trade route, and did not want to submit to Kievan centralism and accept Christianity. After the attack on Croats and Polish marches, Vladimir the Great expanded his realm on the territory of which would be known as Principality of Volhynia and Principality of Halych.