I'm afraid I have no idea what the sentence is trying to say either.  Cungšan is a different person from Wang Gao.  Wang Gao appears to be the maternal great grandfather (or maternal grandfather) of Nurhaci, while Cungšan is apparently also said by some to be an ancestor of Nurhaci, but that is uncertain.  With no source, I don't really know what the sentence is trying to say.  Personally I would just delete Wang Gao as it appears to have no relation to that sentence. I have some books on Chinese history, but right now I'm preoccupied with something else, so I'll have to check it another time.