According to the famous French explorer of religions Jean-Paul Roux, long before the era of the Turks, then living in the Altai, worshiped “man of Heaven”- Tengri. Chinese historians believe that the appearance of the god Tengri they apply no later than the III-V centuries BC.e There is also a version that the word Tengri formed of two words - Tang-Ra - from the Turkic syllable tan – Sunrise and the ancient religious name of sun - Ra. Thus, Tanra refers to the rising sun. But the real etymology of the word still remains largely unsolved. As they called their religion ancient Turks - is unknown. It was based on a cult of cosmic deity Tengri. Idea of Tengri upward its roots to V-IV millennium BC, as the main deity was typical for all Turks and Mongols of the Great Steppe, which gave rise to the French scholar of religions Jean-Paul Roux call it the general term “Tengrians“ . Это и многое другое вы найдете в книге The Cult of Heaven: Tengri (Mirlan Namatov,Akira Asakura and Nurlan Namatov)