Why did Alexander's soldiers reject to cross the Beas River and advance further east?

Alexander reached the Hyphasis (Beas) River in 326 BC during his Indian campaign, but his army refused to march further east. Alexander’s soldiers had been on continuous campaigns for many years before reaching the Beas River. By that time, they were completely exhausted and mentally drained. Many of them were longing to return home after such a long absence, and this feeling of homesickness affected their morale badly. The constant fighting and long marches through unfamiliar regions had taken a heavy toll on them.

At the same time, there were frightening reports about the powerful Magadha kingdom lying further east. It was believed that this kingdom had a very large army along with a huge number of war elephants. Facing such a strong force in a foreign land did not seem wise to the soldiers. Feeling that they could not endure any more hardships, they refused to move forward. Finally, Alexander had no option but to stop his eastward advance.