There is some Background from The Kingdom of Rohan. An interessting point is, that the Name Rohan is an sindarin word.
I like more the name "Horse Lords", like this:
"..It was because of the close affiliation with horses, both in war and peace, that they received their now famous name. Rohirrim (or more properly Rochirrim) is Sindarin for "Horse-lords," and Rohan (or Rochand) means "Land of the Horse-lords." These names were devised by Hallas, son of Cirion the Steward...."
I have bought some thinks from gw and others to make my new LotR Army and Story.
So, look at the blog.