Also known as the Russian Atlantis.
After having conquered some of the Russian lands, Batu Khan heard of Kitezh and ordered his army to advance towards it. The Mongols soon captured Maly Kitezh, forcing Georgy to retreat into the woods towards Bolshoy Kitezh. One of the prisoners told the Mongols about some secret paths to the Lake Svetloyar. The army of the Horde followed Georgy and soon reached the walls of the town. To the surprise of the Mongols, the town had no fortifications whatsoever. Its citizens didn’t even intend to defend themselves and were engaged in fervent praying, asking god for their redemption. On seeing this, the Mongols rushed to the attack, but then stopped. Suddenly, they saw countless fountains of water bursting from under the ground all around them. The attackers fell back and watched the town submerge into the lake. The last thing they saw was a glaring dome of a cathedral with a cross on top of it. Soon, there were only waves.