Other attributes
According to Rus' Primary Chronicle, the first ruler to start uniting East Slavic lands into what has become known as Kievan Rus' was Prince Oleg (879–912). He extended his control from Novgorod south along the Dnieper river valley to protect trade from Khazar incursions from the east, and moved his capital to the more strategic Kiev. Sviatoslav I (died 972) achieved the first major expansion of Kievan Rus' territorial control, fighting a war of conquest against the Khazars. Vladimir the Great (980–1015) introduced Christianity with his own baptism and, by decree, extended it to all inhabitants of Kiev and beyond. Kievan Rus' reached its greatest extent under Yaroslav the Wise (1019–1054); his sons assembled and issued its first written legal code, the Russkaya Pravda ("Rus' Justice"), shortly after his death.
The state began to decline during the late 11th century and the 12th century, disintegrating into various rival regional powers. It was further weakened by economic factors, such as the collapse of Rus' commercial ties to the Byzantine Empire due to the decline of Constantinople and the accompanying diminution of trade routes through its territory. The state finally fell to the Mongol invasion of the 1240s.
Kievan Rus, 1015–1113
