Indian subcontinent can be accessed on land and by sea from three sides. In the past, invaders entered it through West from the side of Afghanistan. It is protected from North by Himalayas which act as a formidable wall. The mountains which cover the India from North West to North East have been responsible for keeping the invaders entering from the North directly and also for creating the weather particularly the Monsoon which gives India respite from sweltering heat and helps in meeting the irrigation requirements and bestow bounteous crops to the region. Its snow capped mountains feed the perennial rivers which sustain the life of teeming masses inhabiting the entire northern India.
The people entering from the West mingled with original people inhabiting the region. Soon their population escalated and they were obliged to spread in search of newer avenues where the conditions existed for habitation. In this process they spread over whole of Ganges valley up to Bengal.
The other entry point was the North East where people from South East Asia and China entered India. In comparison to the Western corridor mentioned earlier, terrain here is more difficult. Also people who came and settled in the North East confined themselves to the Assam and its 6 sister states in the North East. One reason for this might have been the difficult proposition to expand towards West where already stronger kingdoms existed. Secondly the narrow strip called chicken neck area separating the North East states from rest of India must have acted as a bottleneck which might have dissuaded them.
Assam and the 6 other states namely Meghalaya, Tripura, Mizoram, Arunachal Pradesh, Nagaland & Manipur in the North Eastern part of India possess enchanting natural beauty. Due to the lack of industrial progress, the environment is still free of pollution. The natural products are forests of bamboo & teak, crops of rice and vegetables grown on the fertile land on the edges of river Brahmaputra without any application of contaminating fertilizers. Of course most famous product of Assam known all over the world is the tea. You travel by car on any road and along both sides are never ending teas plantations. You can see the women laborers with special kind of baskets hanging from their shoulders plucking the leaves and putting in the baskets.
There is plenty of fish in the rivers. The area is rich in petroleum. In fact, the oldest oil well in India was drilled in Assam at Digboi. The original people are mainly tribals whose customs and rituals are entirely different from rest of India.
The most important migrants to come and and settle in this area came from Yunnan province. First to enter the North East region was Sukhapa, who came with army, his women and nobles. Although initially they did not practiced Hindusim but later Kings leaned towards this religion and ultimately converted to Hinduism. Local inhabitants called them Tai-Ahoms.
As they became more tolerant towards Hinduism, the elements of Hindu mythology entered into their history. Thus it was stated that Brahma created the human beings from a gourd. These people were gentle and pious. But by the time of Treta Yuga, the moral values declined and Indra became worried and sent his grandsons: Khunlung & Khunlai to rule the earth and bring back the old order. These were the progenitors of Tai-Ahoms. They descended to earth facilitated by a golden ladder on the Mung-ri-Mung-ram mountains. Thus the Tai Ahoms, as they won over the local people labeled themselves as Eastern Kshatriyas.