Title, basically. I appreciate the effor that CA has made over the years, but please, please never make the nomadic tribes horde factions. Horde factions have never, ever been fun, and frankly IMO Horde style gameplay doesn't fit the tribes of this game. Hordes made sense in Attila as they were used by the germans to go from one region where they were homeless to another, amassing strength and conquering their way to new lands. But for actual steppe tribes the gameplay doesn't make sense.
The great steppe empires have always had some locations they governed on the steppe, whether they be cities, important locations and sites, and camp grounds that could basically be steppe cities that grew and shrank through the year, but still lay in the same general area(with perhaps some permanent structures). And of course, many steppe tribes, from the Magyars in the west to the Khitans in the far east, would end up conquering and ruling sedentary land. 3K should be no different, as the sort of first third of the "Period of Disunion" as it is known basically ends with the loss of Northern China to the steppe tribes. These tribes did not burn northern china to the ground, they conquered it, ruled it, and eventually got changed by it.