illegal occupation have proceeded slowly; when evictions occur at all, those ejected are usually members of poor, lower castes. Improved communications, roads with motorised traffic, and more frequent government intervention figured in the increased contact that tribal peoples had with outsiders. Commercial highways and cash crops frequently drew non-tribal people into remote areas. By the 1960s and 1970s, the resident nontribal shopkeeper was a permanent feature of many tribal villages. Since shopkeepers often sell goods on credit (demanding high interest), many tribal members have been drawn deeply into debt or mortgaged their land. Merchants also encourage tribals to grow cash crops (such as cotton or castor-oil plants), which increases tribal dependence on the market for necessities. Indebtedness is so extensive that although such transactions are illegal, traders sometimes 'sell' their debtors to other merchants, much like indentured peons. The final blow for some tribes has come when non-tribals, through political jockeying, have managed to gain legal tribal status, that is, to be listed as a Scheduled Tribe. Tribes in the Himalayan foothills have not been as hard-pressed by the intrusions of non-tribal. Historically, their political status was always distinct from the rest of India. Until the British colonial period, there was little effective control by any of the empires centred in peninsular India; the region was populated by autonomous feuding tribes. The British, in efforts to protect the sensitive northeast frontier, followed a policy dubbed the "Inner Line"; non-tribal people were allowed into the areas only with special permission. Post-colonial governments have continued the policy, protecting the Himalayan tribes as part of the strategy to secure the border with China. Ecological threats Many smaller tribal groups are quite sensitive to ecological degradation caused by modernisation. Both commercial forestry and intensive agriculture have proved destructive to the forests that had endured swidden agriculture for many centuries. Adivasis in central part of India have been victims of the Salwa Judum campaign by the Government against the Naxalite insurgency. Government policies on forest reserves have affected tribal peoples profoundly. Government efforts to reserve forests have precipitated armed (if futile) resistance on the part of the tribal peoples involved. Intensive exploitation of forests has often meant allowing outsiders to cut large areas of trees (while the original tribal inhabitants were restricted from cutting), and ultimately replacing mixed forests capable of sustaining tribal life with single-product plantations. Non-tribals have frequently bribed local officials to secure