But when India got independence on 15 August 1947, the country was faced with many problems. The national integration faced great challenges. You must be aware that the partition of the country created two nations, India and Pakistan. The partition caused the worst kind of communal violence. A large number of people who were living in an area for generations had to move to the other area as refugees. You may have watched such scenes in some films and documentaries and serials on the television. Besides, the Indian political leaders were faced with complex issues related to integration of Princely States. There were other factors also that had the potential to generate problems for the unity of the country.
On the eve of independence, India was divided into two sets of territories - the first was the territory known as the British India, on which the British rulers had direct control, and the second being 562 independent Princely States, having indirect control of the British government. When independence was declared, Princely States were given the option to join either of the two nations, India or Pakistan. A few Princely States joined Pakistan, but the rest merged with India. However, there were exceptions like Hyderabad, Jammu and Kashmir, and Junagadh, who wished to remain independent. There were problems with States of Manipur and Tripura also.
In the above stated background, the Constitution of India lays great emphasis on national integration. Its Preamble includes unity and integrity of the nation as a major objective. It also stipulates that every citizen has the fundamental duty to uphold and protect the sovereignty, unity and integrity of India. The Constitution reflects respect for diversity of the country, but it tries to ensure that the unity and integrity is maintained. Which is why, it has made provisions for a centralized federation and opted for a strong central government. You may have noticed this while studying the Lessons on Central government and State governments.