Divide Northern Great Plains of India into regional divisions.

Regional Divisions of the Great Northern Plains of India:

Stretching 2,400 km from the Indus to the Brahmaputra across 7.5 lakh sq. km, the Great Northern Plains are divided into Four Major Regional Divisions (West to East):

• 1. Rajasthan Plain (Thar Desert):
  • Westernmost arid/semi-arid tract drained by the inland Luni River; includes sandy desert (Marusthali), shifting sand dunes (Dhrians), fertile semi-arid plains (Rajasthan Bagar), and saline playa lakes (Sambhar, Didwana).
• 2. Punjab-Haryana Plain:
  • Formed by the deposition of the 5 Indus tributaries (Sutlej, Beas, Ravi); famous for fertile interfluvial Doabs (Bist, Bari, Rachna) and flat alluvial divides; heartland of the Green Revolution.
• 3. Ganga Plain (Largest Sub-Division - 3.75 lakh sq. km):
  • Upper Ganga Plain: Rohilkhand and Doab (Ganga-Yamuna interfluve).
  • Middle Ganga Plain: Eastern UP and Bihar (Avadh, Mithila, Magadh plains).
  • Lower Ganga Plain: West Bengal deltaic plain and the giant Ganga-Brahmaputra Delta (Sundarbans mangrove forest).
• 4. Brahmaputra Plain (Assam Valley):
  • Narrow 720-km long alluvial valley bounded by Himalayas and Meghalaya plateau, drained by Brahmaputra; contains Majuli (world's largest river island).