The high-density region largely corresponds with the Northern plains. It extends from Punjab and Haryana in the west, to Brahmaputra valley in Assam in the east, in between crossing the plains of Uttar Pradesh, Bihar and West Bengal. The region also embraces the plains of Gujarat, North Konkan and Malabar coastal plains, spanning the entire Kerala, the plateaus of Tamil Nadu and Karnataka and coastal belts of Andhra Pradesh and Orissa, ultimately uniting with the Ganga plains.

This expanse as a whole receives a reasonable amount of rainfall. It is also endowed with rechargeable ground water reserves. The rivers irrigating these regions, also help in watering vast zones, with comparative ease, because the region is exceptionally flat and is made of very subterranean and rich alluvial soils. The whole region forms a granary of India. The region is also celebrated for its agro-based industries such as textiles, sugar and edible oils. It is also attended by a superior network of communication. A surplus of low-priced labour is its yet another advantage.

West Bengal now leads this region with the highest density of population per sq km. It is as soaring as 767 persons. Kerala (749), Bihar (497), Uttar Pradesh (473), Punjab (403), Haryana (372), and Assam (286) toe close to Bengal.