Well, not horde. The barbarians roam the plain to the west of the Tamurin River. They are shamanistic and primarily worship the Thunder God since his wrath can be heard from one end of the Great Plain to the other.
There are three types of barbarian tribes.
The nomads travel south during the winters and north again for the brief summers. Each nomadic tribe is very protective of their summer camps. Trespassers are usually killed on sight. The nomads have no formal allegiance with the country of Markshire. They do trade with other tribes on the plains who in turn trade with Markshire. Several of the tribes raid other tribes across the plains.
The fishing tribes are stationary. They have built many tribal villages along the Tamurin. The more closely resemble Native American locations. They maintain warriors to protect them from the raiding tribes and have preyed upon unwary river travelers.
The riders are excellent horsemen and maintain wooden palisade fortresses across the northern portions of the plains. They do not roam very far from these fortresses. They do protect great herds of horses they maintain near their homes.