Despite losing ground on the left flank, the Macedonians still have a fighting chance against the Persians at the Battle of Gaugamela with the ferocious scythe chariots easily countered by their opponents, though the Persian cavalry pose a formidable threat. The pursuit of fugitives by cavalry goes on for days, leading to countless deaths.
The story of Alexander the Great's Persian campaign, including the fall of Persepolis and his gradual Persianization, as well as a brief history of the Persian Empire's founding by Cyrus the Great.