Yes, and little else. A lot of it is land with short grasses as well although that varies by region. I guess I am surprised it would be enough for horses nutritionally.
It was enough for mongol/kereit/naiman/turcik horses (eastern steppe horses?). Of the 5 snouts, only the horse could rely on grass only without peas or roots, which made it the king of the 5, everybody knew how to take care of a horse, even semi-nomad clans had 2 to 3 per adult.
Didn’t those people all domesticate horses? I would think they may have farmed grains to feed the horses. And these introduced horses are meant to be wild.