The North-East

The Himalayan wall, which runs due east-west from Sikkim through Bhutan, bends north-east culminating in the Namcha Barwa (7,755m). It is possible that the Himalayan fold systems extend eastwards into China. However, there is a sharp contrast in tectonic structure west and east of the Dihang-Brahmaputra gorge: south-west/north-east in the NEFA and distinctly north-south further east. This is expressed by a succession of ranges trending south along the Indo-Myanmar border.

The first section of mountain barrier between India and China, east of the Dihang Gorge, is the Mishmi Hills with a high point at Kadusam (5,106m). Drained by the Dihang and Lohit rivers, the area is rugged with dense forest. Then follow the Patkai, Naga, Chin, and Arakan Ranges along the Indo-Myanmar border. These form the great Arakan arc made up of tightly packed parallel ridges and valleys with trellis drainage patterns. Geologically, they are of Mesozoic formation in Arakan, Tertiary in the Naga hills, and Precambrian further north. The ridges rarely exceed 2,000 metres, although some peaks in the Chin, Naga, and Patkai Ranges exceed 3,000 m, the highest being Dalpha Bum (4,578m).

The area is mostly hilly and mountainous. With monsoon rainfall exceeding 2,000 mm, the ranges have dense vegetation of tropical evergreen and deciduous species. The people are a mosaic of Mongoloid tribes. Their villages tend to concentrate on ridge tops to avoid malarial valleys and for defence. Shifting cultivation, known as jhum or taungya (mountain field), is common for cultivating upland rice, maize, and millet with the aid of dibble sticks. Forest products, such as bamboo, honey, wax, and lac, are sources of supplementary income. Lying on the frontier of India and Myanmar, these lands once harboured raiding parties of rival head-hunters. Such rivalries have been superseded now by conflicts over ethnic nationalism (Lintner1996).

The Assam Plateau, more appropriately Meghalaya (Abode of Clouds), is a detached block of the Peninsula beyond the Ganges-Brahmaputra plain. It is formed mainly of pre-Cambrian crystalline rocks with granite intrusions. It extends 240km east-west with an average elevation of 1,830m. Its south flank of sandstones presents a steep slope scoured by the highest rainfall in the world (10,800 mm). Northwards are fragmented outliers of the Mikir and Rangma hills. The plateau is densely forested, although the lower ridges have been converted to secondary woodland through centuries of shifting cultivation. The main crops are maize and upland rice along with potatoes and oranges as cash crops. The people belong to the Garo, Khasi, and Jaintia tribes that speak Mon-Khmer or Tibeto-Burman languages. A matrilineal society persists despite exposure to missionary influence.