India had been among the "leaders" in scientific research spanning Mathematics, Medicine, Chemistry and others.

<http://en.wikipedia.org/wiki/History_of_science_and_technology_in_the_Indian_subcontinent>

Controversial theories of nuclear technology in 1000 BC aside, India's leadership role is true when we talk about the "BC" era and maybe up to 1000 AD.

What went wrong after that? Is the colonization the only reason for India's seeming downfall in scientific advancements?