Debbie--have you seen... Joseph Bruchac's BROTHERS OF THE BUFFALO

Out this year from Fulcrum is Bruchac's Brothers of the Buffalo: A Novel of the Red River War. Here's the synopsis:

1874, the U.S. Army sent troops to subdue and move the Native Americans of the southern plains to reservations.Brothers of the Buffalo follows Private Washington Vance Jr., an African-American calvaryman, and Wolf, a Cheyenne warrior, during the brief and brutal war that followed. Filled with action and suspense from both sides of the battle, this is a tale of conflict and unlikely friendship in the Wild West.

I'll put it in my to-read pile. It is being marketed as for kids in grade 7 and up.