Excerpts from Books and Wikipedia
"The campaign was heralded by the Battle of the Kalka River in May 1223, which resulted in a Mongol victory over the forces of several Rus' principalities. The Mongols nevertheless retreated. A full-scale invasion of Rus' by Batu Khan followed, from 1237 to 1242. The invasion was ended by the Mongol succession process upon the death of Ögedei Khan. All Rus' principalities were forced to submit to Mongol rule and became part of the Golden Horde empire, some of which lasted until 1480." [Wikipedia] "Meanwhile, Subotai and Batu had terrified the first Rus’ city in their path. They captured Riazan’ on December 21 [1237], just before the Christmas Mass. “They burned it all,” says the contemporary Voskresensk Chronicle, “and killed its prince and his princess, and seized the men, women, and children, and monks, nuns, and priests . . .” Moscow fell, as did Kiev after a ten-week siege; so many panicked Kievans crowded into the Church of the Tithe, hoping for safety, that the second floor gave way and the church collapsed inward. , , , By 1240, all of the Rus’ principalities except for Novgorod, the most distant, were under Batu's rule;"