The Moor is flat rolling lands broken by harsh crags and ravines, and a large number of rocky protuberances, also bear in mind the ground is infertile, so only sparse and small grass and shrubs with the occasional tree will grow upon it. So yes, a horse could travel it, but there will be ravines you will have to go around since horses can't climb them, and you will need to bring feed, or else your horses will slowly become malnourished on the Moor.