Prince of Champa by Franklin M. Proud (The Golden Barbarian #2)

Edmund de Beauchamps - Christian knight, lusty adventurer; captured during a daring crusade to the Holy Land, he came to the legendary city of Cambulac as little more than a slave, and stayed to win vast riches and wide renown as the Warlord of Cathay.

In Kubilas Khan he served an elegant and savage lord. Yet for the sake of an exquisite concubine, he would defy the khan and all his armies. Sweeping from the northern city we now call Peking, to the south, where lies modern-day Vietnam, he would rise to triumph and glory...first as the Golden Barbarian, then as PRINCE OF CHAMPA

Paperback, 1985

Goodreads: 3.5