King Porus (also Rai Por) was the King of Paurava. The state falls within the territory of Punjab located between the Jhelum and the Chenab (in Greek, the Hydaspes and the Acesines) rivers in the Punjab and dominions extending to the Beas (in Greek, the Hyphasis). Its capital may have been near the current city of Lahore.
The Greek historian Arrian mentions the river of Hydaspes. The Greeks refer to the Jhelum river as the Hydaspes River where Alexander the Great fought Porus in Battle of the Hydaspes River in 326 BCE.
King Porus was said to be "5 cubits tall", either the implausible 2.3 m (7½ ft) assuming an 18-inch cubit, or the more likely 1.8 m (6 ft) if a 14-inch Macedonian cubit was meant. Either height would be unusually tall for the period.
King Porus fought the Battle of the Hydaspes River with Alexander in 326 BC. After fierce fighting and very heavy casualties on both sides, he was defeated by Alexander in a Pyrrhic victory. The battle is often considered to be Alexander's hardest fought battle, so hard that it caused his army to mutiny against him afterwards. In a famous meeting with Porus - who had suffered many arrow wounds in the battle and had lost his sons, who all chose death in battle rather than surrender -- Alexander reportedly asked him, "How would you like to be treated?" Porus replied, "As befits a king." Alexander was so impressed by the brave and admirable response of King Porus that he released him back to his Kingdom and gave him the captured land of a neighbouring Kingdom whose ruler had fled.
Later, King Porus is reported to have participated in Alexander's conquests further east in India. During the attack and destruction of Sagala, Porus rallied Alexander and supplied elephants as well as 5,000 troops:
In recognition for his support, Alexander gave him the dominion over the territories he had conquered, as far as the Hyphasis:
King Porus seems to have held the position of a Hellenistic satrap for several years after Alexander's departure. He is first mentioned as satrap of the area of the Hydaspes in the text of the Partition of Babylon on 323 BCE. His position was confirmed again in 321 BC at the Partition of Triparadisus.
Greek historians, however, record that he was assassinated, sometime between 321 and 315 BC (317 BC accepted year), by the Thracian general Eudemus, who had remained in charge of the Macedonian armies in the Punjab: