The northern-most range of Himalayas is known as the Great or Inner Himalayas or the Himadri.

Explanation:
The Himadri, also known as the Great Himalayas or Inner Himalayas, is the northernmost range of the Himalayan mountain system.

This range spreads across India, Nepal, Bhutan, and Tibet and extends for over 2,400 kilometres (1,500 miles).

It is the highest and most prominent range of the Himalayas, with an average elevation of over 6,000 meters (19,700 feet) and numerous peaks exceeding 7,000 meters (23,000 feet).

The Himadri is home to some of the highest peaks in the world, including Mount Everest, Kanchenjunga, and Makalu. The range also includes many other well-known peaks such as Nanga Parbat, Annapurna, and Dhaulagiri. These peaks are a significant attraction for mountaineers and adventure enthusiasts from around the world.

The Himadri range is geologically young and was formed by the collision of the Indian and Eurasian tectonic plates. This collision resulted in the uplift of the Himalayas, making it the youngest and highest mountain system on the planet.

The Himadri is also an important ecological region, home to a diverse range of flora and fauna. The range is home to several endangered species, including the snow leopard, red panda, and musk deer.

The rivers that flow down from the Himadri, such as the Ganges, Brahmaputra, and Indus, are the lifeblood of millions of people in South Asia. These rivers provide water for irrigation, drinking, and hydropower generation. The Himalayan glaciers, which are located in the Himadri, are the source of many of these rivers and are rapidly melting due to climate change.

In conclusion, the Himadri, or Great Himalayas, is a remarkable mountain range that has immense ecological, geological, and cultural significance.