Final answer:
The chain of mountains that divide Afghanistan into the north and west, allied with Iran/Central Asia, and the south and east, allied with India, is called the Hindu Kush.
Step-by-step explanation:
The chain of mountains that naturally divide Afghanistan into the north and west, allied with Iran/Central Asia, and the south and east, allied with India, is called the Hindu Kush. The Hindu Kush is a mountain range located in western Pakistan and western Afghanistan. It forms a natural boundary between these regions and separates the Indus River System from the Deccan Plateau.