Rails and Horses — Richard Mueller

In the far future, after the atomic fires have scoured the land, two civilizations rise. One, based on steam trains and regimentation, is trying to reclaim the land and push back the forest barbarians. The barbarians, People of the Horse, want to be left in peace, but the expanding Rail lands won't let them. Caught in a war between these two forces is Stav the Historian and her captor, Peter Bridger, who must teach her that peace may be won between Rails and Horses.