The Muṇḍaka Upanishad is one of the older, "primary" (mukhya) Upanishads commented upon by Shankara. It is associated with the Atharvaveda. It figures as number 5 in the Muktika canon of 108 Upanishads. It has three chapters and each chapter is divided into sub chapters which are called "Khanda". In total this Upanishad has 64 Mantras.