If Indians had a single strong evidence, they would have probably protested when UNESCO announced Lumbini, Nepal as the birth place of Buddha in 1997. Erecting replica of Ashoka 's pillar and digging a pond won't make any place Budhha's birth place. I am sure UNESCO did enough homework before annoucing Lumbini, Nepal as Buddha's birth place.

References:

http://whc.unesco.org/en/list/666/
http://whc.unesco.org/archive/advisory_body_evaluation/666rev.pdf