You need to go back to the history books, from the time of the Chandragupta dynasty, After them, India never existed as we see it today. Even the Arab incursion through present day Rajasthan was facilitated by the rivalry of the various kings of that time. None had a long term vision. To fulfill their own petty ambitions and to get even with their rivals, every king or ruler in India has colluded with the invaders from the West of India, from the time of the first incursion into Sindh in the late 7th century. Be it Rajasthan, Punjab (Remember the Angol - Sikh war of 1842 - who was it that ditched the Khalsa army), Bengal, Rohilakhand, Madras region (comprisiog present day TN, part of AP, Karnataka or Kerala), the Bahmai Kingdoms, the Vijayanagar kingdom, Tipu Sultan's battle with the English army, every where, it was we Indians, who ditched ourself to collude with the foreigners. And in the end, each of these invaders understood the Indian mentality, and the British understood it best.