"[The Mongols] attacked Rus, where they made great havoc, destroying cities and fortresses and slaughtering men; and they laid siege to Kiev, the capital of Rus; after they had besieged the city for a long time, they took it and put the inhabitants to death. When we were journeying through that land we came across countless skulls and bones of dead men lying about on the ground. Kiev had been a very large and thickly populated town, but now it has been reduced almost to nothing, for there are at the present time scarce two hundred houses there and the inhabitants are kept in complete slavery." (Giovanni de Plano Carpini, 1246)
Burundai's overlord, Batu Khan, a grandson of Genghis Khan and founder of the Ulus of Jochi (or Golden Horde) had sacked Yuri's capital Vladimir a couple of weeks before, along with Moscow and Ryazan, and the Battle of the Sit River traditionally marks the end of the Rus principalities' organised military resistance against the Mongol Invasion of what was to become Russia.
Even though war and destruction of a scale Eastern Europe had not seen before (and would not see again until World War II) raged on, the rule of the Golden Horde had begun and was about to shape Russian history for the next 200 years, keeping the region from the development other European countries experienced in the High Middle Ages, establishing Russia's special role between Europe and Eurasia.