Have you forgotten the first encounter with the Thunder Horses already? They have contacts which bind their grandchildren.
Dramatically more expensive as well, especially with opportunity costs accounted for.
Again, honor matters. We ended up with ponies and an accidental marriage over their battle rules. There idea that an opponent might decide it's easier to pay tribute, but would be blind by principle to and aided by the spirits in righting such a profound dishonor if he resorted to perfidy is not an alien concept to him. That's to say nothing about how people tend to react differently to a probe to an extremity and his alternative goal of ravaging the heartland.
They aren't going to settle the march. They don't like it because it's in the way of things they want to raid and burn.
Read it again. I said nothing about his having a grudge. I said that the first thing that will occur to him isn't that tribute is part of a multigenerational vengeance campaign of irrational focus and intensity.
False retreat is classic nomad.