"Internal" frontiers of the Sultanate consisted of the ‘hinterland’ of the garrison towns. During these campaigns, forests were cleared in the Ganga-Yamuna doab and hunter gatherers and pastoralists expelled from their habitat. The "external" frontiers refer to the unconquered territories especially in the southern parts of the subcontinent. Military expeditions into southern India started during the reign of Alauddin Khalji and ended with the reign of Muhammad Tughluq.
