Driven south, the Dravidians remained not only geographically separate, but also politically independent, impervious to the waves of foreign invaders.
The Dravidians are close to all other cultures. 
mnli hypothesis: The Dravidians are close to all other cultures.  premise: Driven south, the Dravidians remained not only geographically separate, but also politically independent, impervious to the waves of foreign invaders.