question: What does legend say Genghis Khan used to obliterate the Kharezmid emporer's place of birth?
sentence: After the capital Samarkand fell, the capital was moved to Bukhara by the remaining men, while Genghis Khan ordered two of his generals and their forces to completely destroy the remnants of the Khwarezmid Empire, including not only royal buildings, but entire towns, populations, and even vast swaths of farmland.