Genghis Khan united the Mongol tribes and built a vast empire through conquest. He was tolerant of different religions and his military strategies of feigned retreat and attacks on horseback allowed him to defeat larger armies. After his death, the Mongol Empire continued expanding under other leaders but grew too large to manage and eventually fractured into khanates. The empire had both positive impacts like increased trade and negative ones as many regions suffered destruction from Mongol invasions.