Primary sources for the History portion of the UPSC syllabus include NCERT textbooks, which provide foundational knowledge, and reference books by established authors like Bipin Chandra and Rajiv Ahir. Aspirants often benefit from comprehensive works on Indian and world history, including ancient, medieval, and modern periods. Additionally, books covering cultural history and major movements enrich understanding. Current affairs related to heritage and archaeology can also be included, making it essential for candidates to stay updated with various historical perspectives and analyses.