Complex sentence: Sakya Pandita preached sermons along his way and arrived at Godan's camp in Liangzhou in 1247, where Mongol troops were exterminating Han Chinese by throwing them in a river.
Split into simpler sentences: Sakya Pandita preached sermons along his way and arrived at Godan's camp in Liangzhou in 1247. There the Mongol troops were exterminating Han Chinese by throwing them in a river.