The Indian campaign of Alexander the Great began in 326 BC. After conquering the
Achaemenid Empire of
Persia, the
Macedonian king (and now high king of the Persian Empire) Alexander launched a campaign into the northwestern
Indian subcontinent (
Pakistan). The
Battle of the Hydaspes river against King
Porus in Punjab is considered by many historians,
Peter Connolly being one of them, as the most costly battle that the armies of Alexander fought.
The rationale for this campaign is usually said to be Alexander's desire to conquer the entire known world, which the Greeks thought ended in north-western India. While considering the conquests of
Carthage and
Rome, Alexander died in
Babylon on June 13, 323 BC. In 321 BC, two years after Alexander's death,
Chandragupta Maurya of
Magadha, founded the
Maurya Empire in India.