Complex sentence: The Khwarezm-Shah returned, captured Samarkand and executed Uthman, then demanded the submission of all leading Karakhanids, and ended the Western Karakhanid state.
Split into simpler sentences: The Khwarezm-Shah returned, captured Samarkand and executed Uthman. He demanded the submission of all leading Karakhanids, and finally extinguished the Western Karakhanid state.