Why this matters now
The Himalayas are a Prelims certainty — the three ranges, regional divisions, and their immense significance. They are also central to GS-3 themes of fragile ecology, disasters (landslides, GLOFs, earthquakes) and climate change (glacier retreat).
Formation
About 50 million years ago, the northward-drifting Indian Plate collided with the Eurasian Plate, crumpling the sediments of the ancient Tethys Sea into fold mountains. The Himalayas are still rising and remain seismically active — which is why the region is earthquake-prone.
The three parallel ranges
| Range | Features |
|---|---|
| Himadri (Greater Himalaya) | Highest, perpetually snow-bound; loftiest peaks (Kanchenjunga, Nanda Devi); granite core |
| Himachal (Lesser Himalaya) | Ranges like Pir Panjal, Dhauladhar, Mahabharat; famous valleys (Kashmir, Kangra) and hill stations |
| Shiwaliks (Outer Himalaya) | Youngest, lowest; longitudinal valleys called Duns (e.g., Dehra Dun) |
Regional divisions
From west to east the Himalayas are divided into the Punjab/Kashmir, Kumaon, Nepal and Assam Himalayas. In the east, the ranges bend sharply south along the India-Myanmar border as the Purvanchal (Patkai, Naga, Manipur, Mizo hills). To the north lie the Trans-Himalayan ranges (Karakoram, Ladakh, Zaskar) with K2.
Significance
- Climatic barrier — block cold Central Asian winds and trap the monsoon, shaping India’s climate;
- Source of perennial rivers — the Indus, Ganga and Brahmaputra;
- Biodiversity — an Eastern Himalaya biodiversity hotspot;
- Strategic — a natural defence frontier (and the locus of India-China/Pakistan boundary issues);
- Resources & tourism — hydropower, forests, pilgrimage and Himalayan tourism.
UPSC angle
Master the three ranges (Himadri-Himachal-Shiwalik), the west-to-east divisions, the Duns, the Purvanchal, and the five-fold significance (climate, rivers, biodiversity, defence, resources).
Frequently asked questions
How were the Himalayas formed?
By the collision of the Indian and Eurasian plates about 50 million years ago, folding ancient Tethys-Sea sediments into mountains; they are still rising.
What are the three ranges of the Himalayas?
The Himadri (Greater Himalaya), the Himachal (Lesser Himalaya) and the Shiwaliks (Outer Himalaya).
What are Duns?
Longitudinal valleys between the Lesser Himalaya and the Shiwaliks — for example, Dehra Dun.
Why are the Himalayas important for India?
They are a climatic barrier, the source of the great perennial rivers, a biodiversity hotspot, a strategic frontier, and a resource and tourism base.