The campaign of Alexander of Macedon reached the borders of western India in the 4th century B.C. Alexander’s army was well-equipped and large and famous for its several successful campaigns. 

The weak and opportunistic rulers of many of the North-Western India had no unity among themselves. Many of them grasped the earliest chance to ally with the invading Alexander. 

But there were some others who put up a brave and unyielding resistance to the might of the Macedonian invader. The most courageous among them was Porus, ruler of the small state on the banks of river Jhelum.

Porus was defeated by the forces of the wily Alexander, but the invader was impressed by the Indian king’s resoluteness, bravery and patriotism. And Alexander returned the kingdom and his other possessions to Porus and went ahead into other eastern areas of India. 

In the meanwhile, Alexander was faced with several problems both within his army and in his empire that forced him to back to Macedonia. Though his Indian campaign was not complete, it left a great influence upon India and India itself had an opportunity to exert its own influence upon the western world culture-wise and in trade relations. 

Alexander’s invasion of India paved the way for the rise of a new cultural stream styled Greco-Buddhism, a commingling of the Hellenistic Greek culture and the Buddhism. This culture that flourished for about eight centuries in a geographic entity embracing the modern Pakistan and Afghanistan became the spring board for the artistic development of the Mahayana Buddhism and it spread in turn to countries like China, Korea, Japan and Central Asia – observes Romila Thapar.