We first hear about Tengrism around the 6th Century as forming amongst the Turkic people of the central Asian steppe, spreading west for a bit with Attila and his crew, then getting mostly overrun by Uighur Manichaeists. What's left gets muddled around with Buryat mythology and a little bit of Buddhist flavor and turned into some elitist thing of a bunch of 'Tngris': some self-made gods and children of gods, of which Genghis Khan's father was said to be one years after he died.
One of the big things we know about Genghis Khan's conquering of Asia and eastern Europe was its religious tolerance; his exemption of Daoists, Buddhists, Christians and Muslims from taxes is sometimes cited as a factor in the downfall of Tengrism. But what I can't find any evidence of is how devoted* to a religion Genghis actually was. Much of the Tngri stuff seems to have been cited by his children as proof of 'divine rule', but I can't find word on whether the man himself believed any of it, whether he went along with it for political/cultural convenience, or if he felt in his marrow that Tengrism was the way to go and the religious tolerance was either a byproduct of that devotion or of a man separating work and pleasure.
- By devotion, I am using the Dictionary.com definition, stating:
adjective: Zealous or ardent in attachment, loyalty, or affection.
I'm not asking if he was a "good Tengrist" (as modern-day understanding of the actual tenets seems murky at best), but if he had strong attachment, loyalty or affection for it, and if so, to which version? Did Genghis Khan believe in the old Mongolian Tengrism with animist sky-worship to any significant degree? Did he believe in the Tngri mini-gods thing that came later? Or was he truly a secular individual?