Linaweaver, Brad. "The Bison Riders"
Divergence: 1520 CE
What if: The Aztecs did not fall to the Spanish.
Summary: An AmerInd from our timeline visits during his dreamquest a North America where the Aztecs war against the North American tribes.
Published: In Tales from the Great Turtle (ed. Piers Anthony and Richard Gilliam), Tor 1994 (0312856288BUY), 1995 (0812534905BUY); and Clownface, 1999 (1584450967BUY).