Crucial historical documents for understanding India's polity include the Constitution of India, which lays the foundation for governance and fundamental rights. Additionally, the Government of India Act 1935 and various judicial verdicts help clarify the evolution of legal frameworks. Furthermore, documents from significant movements such as the Indian Independence Movement provide context on political reforms and federalism in contemporary India. Aspiring candidates must also review significant policy papers and reports by commissions like the Finance Commission for enriching their understanding.