1237
Batu Khan launches Mongol invasion of Rus
A grandson of Genghis with Subutai at his elbow crossed the Volga with over a hundred thousand horsemen. The winter-frozen rivers became Mongol highways into Rus. Ryazan fell in December after a week's siege; its people were massacred in the snow. The invasion opened two and a half centuries of Mongol dominion over the Russian principalities, a period known simply as the Tatar Yoke.
Ryazan falls to Batu Khan in the first Mongol blow
The Russian principality of Ryazan, warned but unable to rally allies in time, fell after five days of siege in December. Grand Prince Yuri was killed and the city reduced to ash. The speed of the disaster stunned the other Rus princes, who had dismissed the Mongol threat as an eastern rumor.
Cumans flee Mongols into Hungary
Tens of thousands of Cuman nomads, shattered by Batu Khan's westward advance, fled across the Carpathians into Hungary. King Bela IV settled them on the Great Plain as border guards, but their pagan customs and livestock trampled Hungarian fields, provoking riots that nearly started a civil war. The Cumans would eventually convert and assimilate, their descendants visible in the place-names and bloodlines of the Hungarian plain.
Teutonic Knights absorb the Livonian Brothers
After their catastrophic defeat by Lithuanians at Saule, the surviving Brothers of the Sword in Livonia were incorporated into the larger Teutonic Order. The northern crusade against Baltic pagans intensified under new leadership, forging what would become medieval Latvia and Estonia. The merged order now controlled a vast arc of territory from the Vistula to the Gulf of Finland, an armed monastic enterprise without parallel.