They annihilated Prince Yuri’s Army. After, they crushed the Russian steppe. In 1239, Batu Khan came back to Russia. Most Russian princes fled because the saw the Mongols’ strength. The Mongols then sacked Kiev(modern day-Ukraine), while Batu sent a small army to check out Poland before going to continue to central Europe. Shortly after, Batu defeated the polish army and went on Central Europe was invaded with 3 armies.
The first army defeated forces from Poland and notably, some Christian military powers, at the battle of Legnica. In 1241, the armies defeated Hungary and brutally killed half of Hungary's population. They also conquered Croatia who was linked to Hungaria at the time. It was then that the Mongols suddenly ended their invasion. Some researchers say they ended their invasion because they saw the European strength to survive and turned back. Others blame Mongol fighting within the empire over the election of a new khan.
However, they had later conquests against Poland, Lithuania, Byzantine Thrace, Bulgaria, Serbia, and once again Hungaria. One might say that the Mongol invasion was pointless, but it also accomplished their goal: to keep invaders out of Mongolia. One claim is that Batu Kahn never intended to advance past Mongolia/Croatia, because by then it was made clear that no one could overthrow Mongolia. In closing, the Mongols accomplished what they went to Europe for and Europe was devastated.