Composed in Vedic Sanskrit , the texts constitute the oldest layer of Sanskrit literature and are the oldest scriptures of Hinduism . The Upanishads are a collection of philosophical texts that form t...Composed in Vedic Sanskrit , the texts constitute the oldest layer of Sanskrit literature and are the oldest scriptures of Hinduism . The Upanishads are a collection of philosophical texts that form the theoretical basis for the Hindu religion. The Mantra language texts: This period includes both the mantra and prose language of the Atharvaveda (Paippalada and Shaunakiya), the Rigveda Khilani, the Samaveda Samhita, and the mantras of the Yajurveda.