John Norman 
Nomads of Gor 

A mysterious nomadic tribe may pose a perilous threat in this alternate-world fantasy adventure in the long-running series. Join celebrated tarnsman Tarl Cabot in his latest adventure on the parallel planet of Gor, with its exotic lifestyle and social norms. Tarl has dedicated his life to ensuring that the Priest-Kings survive the harsh lands of Gor, but a savage tribe that closely guards its secrets has halted his quest. To continue it, Tarl must unravel the mysteries of this strange, private band of nomads called the Wagon People at risk of his life. He is the only man alive who has not trembled in the presence of this mysterious tribe. Now he is embarking on the most perilous adventure of his sojourn on the counter-world of Gor. Will he be accepted by the tribe and learn the secrets they guard with their livesor will he die trying? Rediscover this brilliantly imagined world where men are masters and women live to serve their every desire. Nomads of Gor is the 4th book in the Gorean Saga, but you may enjoy reading the series in any order.