There is no other nation in the entire universe which is as diverse as India and yet remaining united for almost 5000 years by now. Diversity of incredible India can be seen in almost all aspects of life that we can think of. Take a random crowd of about one thousand people in any major city in India today and see the diversity among the people with regard to their colour, language, features, religion, beliefs, attire, mannerisms or even their behaviour. Such a diversity cannot be found in any part of the world, even in Dubai or London. We should learn to appreciate such a diversity bearing in mind the simple fact that we are talking about people of one single nation unlike in Dubai or London.
Many theories have been put forth in the past about the great secret behind this national unity that is unique to only Indian nation. Some people have suggested geo-political reasons for this and some others the racial ones. And quite recently the reasoning reached ridiculous levels when one egocentric and cacophonic eternal attention monger even credited King Akbar for the unity that Indians possess. Some others have credited Emperor Asoka and some others even the British. There are others who give the credit to Adi Sankara citing the four Mutts he set up at the four corners of India for strengthening the religious identity of India. And then there are others who argue strongly for Sardar Patel for uniting all the small geographical kingdoms under a single constitution. But all such physical acts cannot bring about such a unique emotional unity.
There may be some contribution by all these elements in strengthening the national unity of India. However, the ultimate credit for this unique strength of Indian nation shall always rest with Hindu Sanatana Dharma (HSD), which is the hallmark of our national identity. But for its liberal nature, logical strength and unimaginable flexibility, the national identity of India and Indians would have died a natural death during the testing times of Mughal dynasty and colonial rulers which lasted about a full one thousand years. The unique combination of Vedic knowledge and ideological resilience to repudiate any foreign alternatives have stood the test of time. With all its diversities, India remains and will continue to remain a single nation thanks to the mysterious cultural concoction called HSD.