Essential historical documents for understanding Indian polity include the Constitution of India, the Government of India Act of 1935, and various congress resolutions. The Constitution lays the foundational framework for governance, rights, and duties of citizens, while the 1935 Act reveals the historical context of federalism and political structure before independence. Documents like the Preamble, famous speeches by leaders, and key treaties (like the Simla Agreement) provide insights into the nation’s political evolution. Analyzing these documents allows candidates to grasp the complexities of India’s democratic framework and constitutional provisions critical for the UPSC syllabus.