Short answers, pulled from the story.
The word Tengri first appeared in Chinese chronicles during the 4th century BC as the sky god of the Xiongnu. Ancient Turkic and Mongolic languages used various forms like Tengeri, Tangara, and Tanri to describe this concept.
French scholar Jean-Paul Roux introduced the current spelling Tengrism into scientific circulation in 1956. Earlier usage appears in works by 19th-century Kazakh ethnographer Shoqan Walikhanov.
Tengrism served as the state religion for several medieval empires including the Göktürk Khaganate and the Mongol Empire. The cult of Heaven-Tengri became fixed by Orkhon inscriptions used during the 8th to 10th centuries.
Tengrist cosmology divides existence into three worlds: upper heaven, Earth, and underworld darkness. A Tree of Worlds connects these realms at their center while the celestial world has seven layers.
Turkic peoples converted to Islam during the fourteenth century while maintaining syncretic elements within Sufism. Mahmud al-Kashgari described non-Islamic Turks calling sky Tengri around year 1075.
Kyrgyzstan counts approximately 50,000 followers today though government has not recognized the religion officially. Kazakhstan reports over one million practitioners as of 2024 despite lack of official status.