This is the English translation of the Mandala-brahmana Upanishad (belonging to the Shukla-Yajurveda): a minor Sanskrit treatise selected amongst a collection 108 extant upanishads, dating to at least the 1st millennium BC.The Mandala-brahmana-upanishad presents itself in the form of a dialogue between sage Yajnavalkya and Narayana (Purusha of the Sun), after the former went to his world, known as Adityaloka. It discusses various concepts of Yoga.