Complex sentence: Zhou Botong is the younger disciple brother of Wang Chongyang, the founder of the Quanzhen Sect and technically the most senior of all Quanzhen disciples after the death of Wang.
Split into simpler sentences: Zhou Botong is the younger disciple brother of Wang Chongyang, the founder of Quanzhen Sect. He is technically the most senior of all Quanzhen disciples after the death of Wang.