Yuri Danilovich made the town of Mozhaisk and other lands a part of the Muscovy. He had been fighting with the Prince of TverMikhail Yaroslavich for the title of the Grand Prince of Tver since 1304. He received backing from the metropolitan Peter and in 1314 formed an alliance with Novgorod against Tver. After having spent almost 2 years in the Golden Horde and wed Uzbeg Khan's sister Konchaka, Yuri secured khan's backing in his struggle with Tver. In 1317, he returned from the Horde with the Tatar army led by Kavdygai and approached Tver. However, Yuri's army was defeated and his brother Boris and his wife were taken prisoners. Yuri fled to Novgorod and then the Horde, where he persuaded the khan to assassinate his rival Mikhail Yaroslavich (killed in 1318).
During his reign in Vladimir, Yury waged several wars against Volga Bulgaria and founded the fortress of Nizhny Novgorod on the Volga River, to secure the area from Bulgarian attacks.
Yury's sons were soundly defeated near Kolomna, and Yury himself could barely escape to Yaroslavl.
Yury himself was killed on March 4, 1238 in the Battle of the Sit' River, whereby vast Mongol hordes defeated the army of Vladimir-Suzdal.