'Apatani' tribal elder with distinctive top hair knot, village of Ziro.Arunachal Pradesh shares frontiers with China in the north and northeast, Myanmar in the east and Bhutan in the west. Assam and Nagaland form its southern and south-eastern boundaries. It is recognized as one of only 18 biodiversity hotspots around the world. Its nearly 85,000 square kilometres area forms a complex network of mountain ecosystems with deep valleys and high mountains. Arunachal Pradesh is also home to 27 ethnic communities (Scheduled Tribes) with distinctive cultures and rich traditions. Of these, the Apatani are considered to be a very progressive community. In contrast to the others, who practice jhum (slash-and-burn) system of cultivation, the Apatani engage themselves in settled agriculture. Their origin is shrouded in the mystery. In the absence of any authentic documentation, the renowned anthropologist, Christoph von Fuerer-Heimandorf considers them to be of Mongoloid origin.