Early States in South and Southeast Asia
South Asia lies within vast geographic barriers (Figure 17.1). To the north lie the Himalayas, a vast mountain chain extending more than 2,000 km (1,200 miles) from the Hindu Kush in the west to Assam in the east. High passes traverse the mountains into Afghanistan, central Asia, and Tibet, but the most accessible routes are the northwestern defiles into western Afghanistan, Iran, and Baluchistan. The Arabian Sea, the Indian Ocean, and the Bay of Bengal surround the Indian subcontinent, and tropical rain forests restrict access to the east.