User blog comment:Zaarqawi/Why players from YGGDRASIL have been transported to the New World at various periods of time./@comment-27036174-20151108162802

Maybe the world itself sent them to these various points to keep order? The SGGs and the 8GKs prevented humans from going extinct, and the Thirteen Heroes cleaned up the mess left behind by the Greed Kings. Maybe Ainz is here to do something similar for non-human races?