(1219 – 1238)
After the death of his brother Constantine, Yuri II Vsevolodovich again became the Grand Duke.
He waged a successful war against the Mordovians and Kama Bulgarians and built the fortress of Nizhny Novgorod to protect the north-eastern borders. Under him was the first invasion of the Tatars under the leadership of Temuchin, nicknamed Chingiz-Khan.
Until the XIII century Tatars lived separate hordes to the north-west of China. Moving from place to place, they were engaged in cattle breeding, slept in kibits, fed horse meat and koumiss, worshiped idols, sky and fire.
Temuchin, having proclaimed himself a great khan or Genghis Khan, connected all the hordes in one great horde and went to the devastation of China. After conquering northern China, he went to Bukhara, where he sent part of his army to the west.
The Tartar detachment, having crossed the Caucasus, invaded the South Russian steppes inhabited by the Polovtsians. Mstislav Udaloy and other South Russian princes, having united with the Polovtsians, fought against the Tatars on the bank of the Kalki River, which flows into the Azov Sea. The Russian princes, thanks to their strife and the flight of the Polovtsians, were defeated in 1223.
Soon Temujin died. His son, Ugedei, was proclaimed a great khan. In 1235, Ogedei sent his nephew Batu to conquer Europe.
After defeating the Kama Bulgarians, the Tatars entered the Ryazan land. After the capture of Ryazan in 1237 Baty went to the region of Suzdal. Taking Moscow, they approached Vladimir on the Klyazma.
Yuri II was not in the city, he was building an army to fight the Tatars. The family of the Grand Duke with Bishop Mitrophan took refuge in the Assumption Cathedral, where he died in the fire.
On the banks of the City River, in 1238, the Tatars met with Grand Duke Yuri II. There was a battle, the Russians were defeated, the Grand Duke fell. The Tatars took Tver, Torzhok and, not reaching 100 miles to Novgorod, turned to the southeast.