I suspect the Garleans haven't put a huge amount of effort into controlling much of the Xaela. Some tribes would almost certainly be influenced but I suspect since they generally all live in a great steppe. the Garleans would have limited interest. Rounding up all the tribes and pushing them into camps would likely not be worth the effort and likewise the tribes aren't likely to unite so aren't a huge threat. I suspect the Garleans would mostly ignore the Xaela unless the Xaela actually had something they wanted or roamed near areas that the Garleans had an interest in.

Frankly I suspect a great number of the tribes the Garleans would look down on as savages.