Human–Environment Interactions: The Tropical and the Subtropical Region

The part of land where all the water collects and flows into one river — a drainage basin. For example, the Ganga basin — the entire region from the Himalayas to the Ganga-Sundarbans where rainfall drains into the Ganga.

Equatorial — because it is located near the Equator: hot throughout the year (25–30°C) and daily rainfall (200 cm+). That is why the world's largest thick green rainforest is found there.

Jaguar (large cat), sloth (a slow animal that hangs upside down from trees), anaconda (largest snake), piranha (fish with sharp teeth), toucan and macaw (birds). Each one is a guest in the green home of the jungle.

Paddy (rice) — the most important crop (wet land + monsoon), jute (for bags and sacks), tea (Darjeeling's finest), pulses, and mustard. The river's soil (from floods) acts as fertilizer every year — making farming excellent.

The river provided: water (for drinking and farming), fertile soil (replenished every year by floods), transport (boats and cities along the riverbanks), and fish. That is why civilization has grown here for thousands of years — making it the world's most densely populated region.

Tsangpo. It originates from the northern side of the Himalayas and flows a long distance through Tibet, then enters India (Arunachal Pradesh — known as Siang or Dihang), where it is called the Brahmaputra, and finally meets the Ganga (Jamuna) in Bangladesh to form the Sundarbans delta.