The Vedas are the oldest and most authoritative sources of Indian Knowledge. They contain hymns, philosophical ideas, rituals and early scientific observations. The four Vedas are: Rigveda, Yajurveda, Samaveda and Atharvaveda. These texts provide insights into astronomy, ecology, mathematics and early medicines, forming the foundation of many later knowledge traditions. Each Veda consists of four parts : Samhita (hymns), Brahmana (ritual explanations), Aranyaka (forest treatises) and Upanishads (Philosophical teachings). Epics (Itihasa):- Ancient Indian epics serve as major sources of social, ethical and political wisdom. Smriti means “That which is remembered”. These texts were composed by sages based on the principles of Shruti and are considered secondary authority, which include Dharmashastras, Manusmriti, Epics, Purunas. Many ancient texts were originally written in Sanskrit, Pali, and Prakrit making translation essential for modern scholars. Several translated versions exist in English and other languages enabling wider study. Scholars from India and abroad have translated these texts to make them accessible to modern readers.

Abhishek Kumar, Dr. Ashok Kumar Sah, "Study on the Applications of Astronomy in Buddhist and Hindu Calendar in the Sources of Indian Knowledge System" International Journal of Scientific Research and Engineering Development, V9(5): Page(1456-1460) September - October 2026. ISSN: 2581-7175. www.ijsred.com. Published by Scientific and Academic Research Publishing.