Tiahuanaco, the ancient empire of the Aymara Indians, was the first great empire of the New World, richer and larger than the empires of the Inca and Maya. This study covers the 15,000 year history of the Aymara civilization, from the time of their great empire - 800 years before the Inca - to the life of their present-day descendants. Alan Kolata offers new insight into the popular subject of native people's philosophies of nature. The Aymara were nature worshippers with a unique philosophy of respect for the natural world, and an elaborate religion. They were ruled by Spirit Kings who presided over the natural world, and they built religious temples and practised exotic rituals, such as animal and human sacrifices, to worship nature. "Valley of the Spirits" tells how the author has helped the contemporary descendants to rediscover their ancient past and reclaim their native culture. He explains how he has re-educated them in the use of the ancient, organic farming techniques of their ancestors, resulting in better crops.