Berossus was a Hellenistic-era Babylonian writer, a priest of Bel Marduk and astronomer who wrote in the Koine Greek language, and who was active at the beginning of the 3rd century BC. He was born during or before Alexander the Great’s reign over Babylon (330–323 BC), with the earliest date suggested as 340 BC. Using ancient Babylonian records and texts that are now lost, Berossus published the Babyloniaca (hereafter, History of Babylonia) in three books some time around 290–278 BC.