Kurbustu is the master of the celestial realm in Tuvan cosmology, standing at the head of the ranked heavenly lords known as azar who inhabit the layered skies. His name travelled a long road: it descends from the Iranian Ahura Mazda by way of Sogdian and Uighur Buddhism and the Mongolian Qormusta Tngri, and was absorbed into the Sayan-Altai shamanic world as the supreme sky-figure. In shaman songs the upper-world practitioner ascends through the heavens toward Kurbustu and his azar host, who form the bright counterweight to Erlik's subterranean domain. Sources differ on how sharply he is distinguished from the diffuse notion of the sky itself, since Tuvan tradition tends to address the heavens as a graded hierarchy of lords rather than a single throned god.