User blog comment:Nomad27/Predictions of what will Occur in Volume 10./@comment-64.228.198.175-20151117143017/@comment-27099834-20151118024318

The human kingdoms so far in the story seem to be on a small scale compared to those at the centre of the continent. In Vol 9 intermission the Draconic Queen stated "Man eating races were quite common. 3 out of the 6 biggest countries on the continent viewed humans as food", so there's definitely much stronger nations east* of where Nazarick is. The NW also has a history of humans being hunted until the arrival of the 8GK. Being constantly oppressed would also explain how an extremist nation like the Slane Theocracy came to be. The story seems to be shifting in development to a major conflict near the Draconic Kingdom with said man-eating nations and whatever unknown force that's driving them.

Katze plains coming under the control of Ainz is perfect for him. He always wanted to test whether there are any differences between natural spawning undead vs summoned ones eg if naturally spawned Death Knight could learn martial arts.