Complex sentence: Zhang was said to have massacred large number of people in Sichuan with Chengdu reduced to a virtual ghost town frequented by tigers, and resulted in the resettlement of millions of people from other provinces during the Qing Dynasty.
Split into simpler sentences: Zhang was said to have massacred large number of people in Sichuan and Chengdu was reduced to a virtual ghost town frequented by tigers. The depopulation of Sichuan necessitated the resettlement of millions of people from other provinces during the Qing Dynasty.