Why Did Alexander Enter The Indus River

Following the conquest of the mighty Persian Empire and the death of King Darius, Alexander set out to consolidate his kingdom. However, he now has his mind on a bigger prize, India. Alexander reached the Indus River, the gateway to India, in spring 326 B.C. When he arrived, he met up with Hephaestion, whom he had sent ahead to ready the river crossing. The Indus River is one of the largest Rivers in India, second only to the Ganges. It is no small task to move an army across such a large river, but Alexander had a brilliant solution. He would have Hephaestion construct a pontoon bridge, which is a bridge constructed out of boats that the Macedonians could rope together, creating a rather quick solution to the problem.
Entering the Punjab Region, or the land of five rivers, Alexander was greeted by a prince named Taxiles, who controlled a large section of land east of the Indus. Taxiles welcomed Alexander with open arms, seeking to ally with him against his rival Porus. They immediately became great friends, and many gifts were exchanged between them. Alexander rested his army for a short time at Taxilia, the largest city between the Indus and the Hydaspes and owned by Alexander’s new ally.
Alexander would

Secondly, he led a small group of cavalry up and down the western bank of the river. This served two purposes, they were able to survey the terrain to look for a potential crossing point, but more importantly, Porus’ cavalry on the other side of the river, being paranoid about a secret crossing, would mirror their movements. Alexander did this every night for several weeks. Eventually, the Indians stopped shadowing their movements on the opposite banks. They had become used to the Macedonians doing this every night and therefore had been lulled into a false sense of security. This is going exactly as Alexander