Self-determination
In 1947, India gained independence from the British Empire. The empire was in decline but adapted to these circumstances by creating the British Commonwealth—since 1949 the Commonwealth of Nations—which is a free association of equal states. As India obtained its independence, multiple ethnic conflicts emerged in relation to the formation of a statehood during the Partition of India which resulted in Islamic Pakistan and Secular India. Before the advent of the British, no empire based in mainland India had controlled any part of what now makes up the country's Northeast, part of the reason for the ongoing insurgency in Northeast India. In 1971 Bangladesh obtained independence from Pakistan.
Jammu and Kashmir (princely state)
In 1947, Britain gave up its rule of India. The Indian Independence Act divided British India into two independent states, the Dominion of Pakistan and Dominion of India. According to the Act, "the suzerainty of His Majesty over the Indian States lapses, and with it, all treaties and agreements in force at the date of the passing of this Act between His Majesty and the rulers of Indian States." So each of the princely states was now free to join India or Pakistan or to remain independent. Most of the princes acceded to one or the other of the two nations.