classification system, the Nepal Terai experiences a tropical savanna climate type with dry winters and hot summers, a mean annual temperature of , a mean annual rainfall of in the west and in the east. Ethnic groups Tharu and Dhimal people are the indigenous inhabitants of the Terai forests. Several Tharu subgroups are scattered over most of the Nepal and Indian Terai. They used to be semi-nomadic, practised shifting cultivation and collected wild fruits, vegetables and medicinal herbs. They have been living in the Terai for many centuries and reputedly had an innate resistance to malaria. Dhimal reside in the eastern Nepal Terai, viz Sunsari, Morang and Jhapa districts. In the past, they lived in the fringes of the forest and conducted a semi-nomadic life to evade outbreaks of diseases. Today, they are subsistence farmers. The Bhoksa people are indigenous to the western Terai in the Indian Kumaon division. Maithils inhabit the Indian Terai in Bihar and the eastern Terai in Nepal. Bhojpuri people reside in the central and eastern Terai, and Awadhi people live in the central and western Terai. Bantawa people reside foremost in two districts of the eastern Terai in Nepal. Following the malaria eradication program using DDT in the 1960s, a large and heterogeneous non-Tharu population settled in the Nepal Terai. Pahari people from the mid-hills including Bahun, Chhetri and Newar moved to the plains in search of arable land. In the rural parts of the Nepal Terai, distribution and value of land determine economic hierarchy to a large extent. High caste migrants from the hills and traditional Tharu landlords who own agriculturally productive land constitute the upper level of the economic hierarchy. The poor are the landless or near landless Terai Dalits, including the Musahar, Chamar and Mallah. Several Chepang people also live in Nepal's central and eastern Terai districts. As of June 2011, the human population in the Nepal Terai totalled 13,318,705 people in 2,527,558 households comprising more than 120 different ethnic groups and castes such as Badi, Chamling, Ghale, Kumal, Limbu, Magar, Muslim, Rajbanshi, Teli, Thakuri, Yadav and Majhi speaking people. History The Muslim invasion of northern India during the 14th century caused Hindu and Buddhist people to seek refuge from religious persecution. Rajput nobles and their entourage migrated to the Himalayan foothills and gained control over the region from Kashmir to the eastern Terai during the next three centuries. Until the mid