• The coastal plains constitute the states of Tamil Nadu in east and Kerala on west. In Tamil Nadu, the rivers are seasonal. As a result, the people of this region have depended more on tank irrigation since the early times. However, Kaveri delta has been the major region of human attraction.

• It provided opportunity for the cultivation of rice and witnessed the flourishing of the Sangam culture in the early historical period. The ports, such as Arikamedu and Kaveripattinam gave impetus to the Indo-Roman trade in the early centuries of the Christian era. The Tamil region evolved a distinct linguistic and cultural identity of its own.

• The Raichur doab, for its rice cultivation, has been known as the ‘rice-bowl’ of South India. It has been the bone of contention between different kingdoms.