Why did mongols attack kiev?

The Mongols attacked Kyiv in 1240 during their westward expansion under Batu Khan, a grandson of Genghis Khan. The city was a significant political and economic center in Kievan Rus', which posed a threat to Mongol dominance in the region. Additionally, the Mongols sought to subdue various principalities and consolidate their control over Eastern Europe. The siege resulted in the city's destruction and marked a pivotal moment in the Mongol conquest of the area.