Arunachal finds mention in the literature of Kalika Purana and Mahabharata. This place is supposed to be the Prabhu Mountains of the Puranas. It was here that sage Parashuram washed away his sin, sage Vyasa meditated, King Bhishmaka founded his kingdom and Lord Krishna married his consort Rukmini.
It is a land of lush green forests, deep river valleys and beautiful plateaus. The land is mostly mountainous with the Himalayan range along the northern borders criss-crossed with ranges running north-south. These divide the state into five river valleys: the Kameng, the Subansiri, the Siang, the Lohit and the Tirap. All these are fed by snow from the Himalayas and countless rivers and rivulets.
The weather and the climate of Arunachal Pradesh are quite distinct from the rest of the country. The climate of the State is dominated by the Himalayan system and the altitudanal variations. The climate is highly hot and humid at the lower altitudes and in the valleys covered by swampy dense forest particularly in the eastern section, while it becomes exceedingly cold in the higher altitudes. Average temperature during the winter months range from 15 to 21 degree celsius and 22 to 30 degree celsius during monsoon.
Between June and August the temperature may go up to 40-42 degree celsius.The rainfall of Arunachal Pradesh in amongst the heaviest in the country. The annual average rainfall in Arunachal Pradesh is more than 350cm. There are 26 major tribes and a number of sub-tribes inhabiting the area. Most of these communities are ethnically similar, having derived from original Mongoloid stock but their geographical isolation from each other has brought amongst them certain distinctive characteristics in language, dress and customs.
The second group of people of Adis, Akas, Apatanis, Bungnis, Nishis, Mishmis, Mijis, Thangsos etc. who worship the Sun and the Moon God, namely, Donyi-Polo and Abo-Tani, the original ancestor for most of these tribes. Their religious rituals, largely coincide with the phases of agricultural cycles. They traditionally practise Jhuming or shifting cultivation. The third group comprises Noctes and Wanchos in the Tirap district . These are hardy people known for their structured village society in which the hereditary village chief still plays a vital role. The Noctes also practise elementary form of Vaishnavism.