The B?hadara?yaka Upanishad is one of the older, "primary" (mukhya) Upanishads. It is contained within the Shatapatha Brahmana, and its status as an independent Upanishad may be considered a secondary extraction of a portion of the Brahmana text. This makes it one of the oldest texts of the Upanishad corpus. It is largely the oldest Upanishad, excluding some parts which were composed after the Chandogya.