The Aryan Invasion Theory, although thoroughly discredited, still has deep impressions on the psyche of (confused) Indians. Along with Caste system, it is the poster child for the harm done by Videshi Indology. The most concrete illustration of the harm done by Aryan-Dravidian divide is the current politics of Tamil Nadu.
Dr Nagaswamy recently published a book titled Tamil Nadu: The Land of the Vedas which collects evidence against the Dravidian theory and sets the record straight. The following conversation between Rajiv Malthotra and Tamil scholar Dr. R. Nagaswamy talks about the book and much more.
More on the topic in this article on Pragyata.