Warpath by Tony Daniel

In the far distant future the bulk of humanity has spread across the galaxy — only to discover that American Indians got there first!
Long before Columbus, a tribe of Mississippi Indians discovered the metaphysical effect that makes space travel possible and paddled their birchbark canoes to distant worlds light-years from Earth. Now an interstellar Indian nation, armed with spears and guided missile, comes into conflict with colonists from a technological civilization so advanced that even their homes and newspapers possess artificial intelligences. History seems poised to repeat itself, but on a galactic scale.

And on the icy planet Candle, only one lonely man stands between the universe and an endless… Warpath!