Tribesmen of Gor - John Norman

Tarl Cabot must prove his final loyalty to the harsh and caste-bound planet known as Counter Earth. "Surrender Gor," reads a message sent from the Others, a mysterious people from the worlds of steel. Either the proud rulers of Gor must submit or be destroyed. Now Tarl is leaving the decadent city of Port Kar to wander in the wilds of Gor, taking up the sword to defend his rulers and enemies, the Priest-Kings. For he knows that the fate of his home planet, Earth, is inextricably tied to the fate of Gor.
Rediscover this brilliantly imagined world where men are masters and women live to serve their every desire. Tribesmen of Gor is the 10th book in the Gorean Saga, but you may enjoy reading the series in any order.