Complex sentence: However, the Han are looking for Hae Mosu, and discovering that the man the princess was sheltering looked like (and was) Hae Mosu, they raze the tribe to the ground.
Split into simpler sentences: However, the Han are looking for Hae Mosu, and discovering that the man the princess was sheltering looked like and turns out to be Hae Mosu. As a result, they raze the tribe to the ground.