Battle of Gaugamela
The Battle of Gaugamela, in which Alexander the Great defeated Darius III of Persia, took place in 331 BC approximately west of Erbil. After the battle, Darius managed to flee to the city. (Somewhat inaccurately, the confrontation is sometimes known as the "Battle of Arbela".) Subsequently, Arbela was part of Alexander's Empire. After the death of Alexander the Great in 323 BC, Arbela became part of the Hellenistic Seleucid Empire.