India is what is today due to perhaps two MAJOR factors.
- Indian nationalism!
- Indian military!
That is!
Majority of the people of modern day India has decided to be proud of their country no matter what.
Majority of the people of modern day India has decided to be respectful of their country no matter what.
Majority of the people of modern day India has decided to not bring bad name to their country no matter what.
Majority of the people of modern day India has decided to be positive about their future no matter what.
And if a group big or small decides to go against the Indian nationalistic view and becomes violent, then Indian military can go in and club them to submission.
Indian nationalist view also allows majority of Indians to be respectful and work closely with the West.
Why it so?
There could be many reasons.
Perhaps they have realized after centuries of invasions and subjugation that sticking together (even when it is hot and humid and smelly), will help them survive.
Perhaps they all have learned from the "invaders" most of the things that help survive as a group.
Perhaps, Indian culture has evolved to a point where they can figure out things that will keep their country together.
India will stay together as long majority is nationalist and they remain to have a strong military.