Cover art
Roberts, John Maddox. King of the Woods. Tor 1986.

Roberts, John Maddox. King of the Wood
Divergence: 995 CE
What if: Pagan Vikings fleeing forced conversion to Christianity established strong settlements in North America, and were later joined by Saxons.
Summary: An outlaw Saxon prince from eastern North America takes part in the Mongol conquest of Mexico.
Published: Doubleday 1983 (0385175841BUY); Tor 1986 (0812552067BUY, 0812552075).