User blog comment:Kaido King of the Beasts/Chapter 818: Stepping Stones to One Piece/@comment-4374114-20160303195953/@comment-2226235-20160305080942

It might also be that the Yonko don't have as much influence outside the New World. It seems like most of their activities are focused in the New World, since (aside from Whitebeard at Marineford) we haven't heard anything about them doing much outside of it.