NOTE 69 to range from 4900 metres to 7000 metres, the setting offers a wide variety of topography, vegetation and wild life. The outward reaches of the hills and valleys touch on the international frontiers with Bhutan, China, Burma and Thailand. Among the rivers, the Siang (which is known as the Tsangpo in Tibet and is afterwards denoted as the Brahmaputra in Assam) flows through Arunachal Pradesh, almost bisecting the state in two natural parts. Kameng, Dibang, Lohit and Subansiri are also mighty rivers that enrich the upper reaches of the province. Furthermore, a number of small rivers and rivulets like Tirap, Tisa, Kamlong, Sisi, Kamala and others flow across the southern region and meet the Brahmaputra downwards. The coniferous trees such as pine, juniper, silver fir, rhododendron, and local 'holong-makai' as well as wild strawberry make the scenery immensely colourful. In the higher altitude, the vegetation of alpine varieties reach out to the snow-line. This is the environment which nestles the villages inhabited by various local tribes. According to the Census Report of 1981, there are 110 tribes and sub-tribes distributed over the whole of Arunachal. The state is mostly rural, with the slender urban setting consisting of the headquarters in different districts and the metropolis at Itanagar. Among the tribes, Adi, Khampti and Apatani figure prominently. Each tribe has traditionally lived in a village or a cluster of neighbouring villages and maintained a social distance with the other tribes. Every village of moderate size used to be recognised, till recent times, as an independent entity and clearly demarcated by its cultivable jhum fields, fishing areas and forests. The traditional economy was agro-based, with a local network of interdependence between agriculture and crafts in the villages. The jhum or shifting cultivation was almost the only method of tillage, resulting in erosion of fertility and a poor rate of production. Double-cropping was scarcely undertaken. Inter-village transactions were mostly carried out in the weekly fairs through barter, rice and cattle being the usual forms of exchange. However, a slender amount of agricultural surplus used to emanate after the normal consumption by the village community. A portion of this surplus has been traditionally appropriated by the head or the seniormost leader (sometimes known as the Gaon-burah) who, in his turn, would send another part of the surplus to the chief of the Concerned tribe. The chief is entitled to a kind of proprietary right over the land cultivated in the villages inhabited by his fellow tribals. The community of tribal tillers in a village traditionally enjoy usufructory right over the land they cultivate jointly. Similar conventions of proprietary and usufructory rights are extended to the use of forests. The whole rural structure has been, thus, permeated by a convergence of the ingredients of tribal community with the feudal elements of local variety.