Mongol-Tatar Invasion

From Moscowiki

Kievian Rus consisted of many principalities, each with a prince eager to reign in Kiev. Their avidity and thirst for power caused many bloody intrigues and intestine strives. This led to disunion and weakening of the state. As a result in 1237 Russians fell easy victims to the well-organized Mongolian troops under the leadership of Batu Khan. In 1237 Tatar-Mongolian army occupied Ryazan, then Moscow, Vladimir, Kozelsk and finally in 1240 ‘the Mother of Russian cities’, Kiev, was conquered and burnt down by the bellicose nomads. The fall of Kiev signified the decline of the Kievian Rus. For the next 240 years abased Russia paid exorbitant yearly tributes to the khans, though Russian princes were allowed to govern the country themselves.