Alexander, the son of King Philip of Macedonia, ascended the throne at the age of $20.$
He wanted to be a world champion.
His attacks on India are known as "Macedonia" attacks.
Alexander defeated Darius $III$ of Iran in the battle of Arbella and prepared for an invasion of India.
Alexander's army reached the Hindu Kush Mountain in $327\ BC$ to invade India.
Then in 10 days the army crossed this mountain and reached "Nasiya" in the valley of Kabul.
In order to invade India from Nazia, Alexander divided his army into two parts: one led by himself and the other led by two of his generals.
They proceeded on the way to Khyberghat under the guidance of Ambhikumar.
But on the way, Ashtesh, the king of the Ashtak tribe, bravely confronted them and defended his capital Pushpaklavati for $30$ days. Only after he was killed in battle did the Greek army advance.
The other part of the army marched towards Peshawar under Alexander.
The Kutar, Panjkaur, and Swat valleys along the way were hard hit by the Ashwayan population.
But they all lost, the East Yashvakayan tribe bravely faced Alexander from their fort called "Mussag".
Alexander was wounded in a fort as he was about to break through their forts.
Its price was to be paid by the people of the whole fort.
Alexander killed about $7000$ people in the fort.
After this he conquered the strongest Arson's fort of Ashvakayo and found Ambhikumar in Takshashila.
He conquered small forts, Takshashila, Punjab, Glausai, Priprama, Kath etc. and expanded his kingdom on the northwestern border of India.
In the region between Jhelum and Chenab, the Raghuvanshi king Pravartak $($Puru, or Porus$)$ did not surrender and bravely faced Alexander's army.
The promoter was wounded in battle and captured by Alexander's army.
Alexander appreciated it and returned the kingdom.
When Alexander's army reached the banks of the Beas River after destroying the fort, Alexander's troops heard that a large army of the Magadha Empire was ready for battle on the opposite bank of the river.
So the soldiers refused to move forward and Alexander had to retreat.
He handed over his conquered territories to General Seleucus Niketar.
Thus, it only took Alexander three and a half years to conquer the small states on the northwestern frontier.
There was no occasion to face a powerful empire like Magadha.
Not only that, Alexander's disciplined army clearly refused to cross the Beas River.