In 327 BC Alexander, in his march against Emperor Darius empire, came into India.This lasted for 2 years. There is no record in Indian sources of his exploits, and there was little consequence of his invasion in the long term. He came to India to reach the easternmost parts of Darius' empire - reach the ocean. This ran into trouble along the Sindhu river (Indus), and he then went along the river, fighting many battles - Puru, subduing of the Gana-Sanghas, Battle with the Malloi where he was injured - and exacted a brutal revenge.

He is supposed to have built an alliance with Ambhi of Taxila, and attacked Puru on the banks of the Jhelum. One historical source even claims that the name Puru may have been referring to the Puru Tribe, which has inhabited the area since Rug-vedic times. Alexanders' invasion is not mentioned in any Indian Texts; we only have Macedonian records, No one can say for sure how accurate they are. Some of them state the presence of giant ants that dig for Gold! Sample this observation:

There are men said to be 10 feet tall and six feet wide; some had ears reaching down to their feet - Megasthenes in Ancient India as described by Megasthenes and Arrian. This does not mean all of their observations were hogwash, some were accurate. They are supposed to be a mix of fact and fable.

In all history texts that I have read (please dont refer online or western sources for this) the entire Puru episode does not include more than 4 lines. There is no guarantee of the accuracy of that episode. That battle did take place is about the only thing that is certain; as is the fact that Alexander won. As to the rest - could be conjecture, or could be fact, No Idea.

The most important result of Alexander's exploits is sadly forgotten - the emergence of the Mourya Dynasty... but that is another story

Ref: Early India - Romila Thapar; Land Of The Seven Rivers- Sanjeev Sanyal