User blog comment:Jallu/Soul king and "king"(yhwach)/@comment-6916556-20140201171314

I highly doubt it. Yhwach is only 2000 years old at the most. The quincy war was around then, and the shinigami probably didn't take that long to discover their existence. In any case Yhwach is younger than Yamamoto and his birth was shown in a time when people worshipped Yahweh, so probably 2000-1200 years ago.

Rukia states that the soul society has a 1 million year history, and the soul society can only exist in tandem with the real world with the soul kings presence. I would say that he is probably 1 million years old. I am sure the reason for Yhwach being born as a deaf, blind and dumb baby has something to do with soul king, but I doubt they are on the same level of being.