Battle of the Hydaspes

After gaining control of the former Achaemenid satrapy of Gandhara, including the city of Taxila, Alexander advanced into Punjab, where he engaged in the battle against the regional king Porus, whom Alexander defeated in the Battle of the Hydaspes in 326 BC, but was so impressed by the demeanor with which the king carried himself that he allowed Porus to continue governing his own kingdom as a satrap. Although victorious, the Battle of the Hydaspes was also the most costly battle fought by the Macedonians. Now Macedonian Empire annexes large areas of the Punjab region from the Hydaspes to the Hyphasis.