Arapahoe only sounds odd if you don't know that it is the name of a First Nations group and member of the Algonquian language family. Their name is more usually spelled Arapaho, and you can find them described there. To that good node, I can only add a few details. They were often called "dog eaters" by their neighbours, which tells you a little about their real or purported diet. They are thought to be related to the Cheyenne and Blackfoot, but migrated before recorded history and split into several groups. Today, the Atsina or Gros Ventre reside with the Assiniboin on a reservation in Montana; the southern Arapaho(e) live with the Cheyenne in Oklahoma, and the northern Arapaho(e) are centred with their former enemies, the Shoshone, on a reservation near Yellowstone National Park. This latter group retained the sacred regalia of the nation and thus claim to represent all the Arapaho.
For an oral history of the nation as recounted by Puis Moss, an elder and direct descendant of Chief Black Coal, see
http://www.wyomingcompanion.com/wcwrr.html#arapaho