Principal Upanishads, also known as Mukhya Upanishads, are the most ancient and widely studied Upanishads of Hinduism. Composed between 800 BCE to the start of common era, these texts are connected to the Vedic tradition.[1]
The Principal Upanishads, which were composed probably between 600 and 300 BCE, constitute the concluding portion of the Veda.[2] According to most Hinduism traditions, ten Upanishads are considered as Principal Upanishads, but some scholars now are including Śvetāśvatara, Kauṣītaki and Maitrāyaṇīya into the list.[3][4][5] The founders of the major schools of Vedanta, viz., Adi Shankara and Madhvacharya wrote bhāṣyas (commentaries) on these ten Principal Upanishads. Even though Ramanuja did not write individual commentaries on Principal Upanishads, he quoted many hundreds of quotations from Upanishads in his Sri Bhasya. In the Ramanuja lineage, one of his followers, Rangaramanuja, wrote commentaries on almost all of the Principal Upanishads around the 1600s.[6][7]
The Principal Upanishads are accepted as śruti by all Hindus, or the most important scriptures of Hinduism.[8] The Principal Upanishads are separated into three categories: prose (Taittirīya, Aitareya, Chāndogya, Bṛhadāraṇyaka), verse (Īśā, Kaṭha, Muṇḍaka), and prose (classical Sanskrit) (Māṇḍūkya).[2]
^John G. Arapura (2012). Gnosis and the Question of Thought in Vedānta: Dialogue with the Foundations. Springer. p. 57. ISBN978-94-009-4339-1.; Quote: "These are the Isa, Kena, Katha, Prasna, Mundaka, Mandukya, Aitareya, Taittiriya, Brhadaranyaka, Chandogya and Svetasvatara. To this list is usually added the Kausitaki and Maitrayaniya (or Maitri) to make the thirteen Principal Upanishads, a canon which has found favour with most scholars of the present day."
^Madabhushini Narasimhacharya (2004). Sri Ramanuja. Sahitya Akademi. p. 32. ISBN9788126018338. As for Ramanuja, his commentary on the Gita and the Brahmasutra are quite well known as conforming to this practice . But he did not write any regular commentary on the Upanishads as other philosophers like, say, Sankara and Anandatirtha (Madhva) did.
