Thermopylae /θərˈmɒpəli/ (Ancient and Katharevousa Greek Θερμοπύλαι, Demotic Θερμοπύλες: "hot gateway") is a location in Greece where a narrow coastal passage existed in antiquity.It derives its name from several natural hot water springs. It is primarily known for the Battle of Thermopylae in 480 BC in which an outnumbered Greek force of roughly 7,000 men temporarily held off advancing Persians under Xerxes, numbering in the hundreds of thousands, and the term since has been used to reference heroic resistance against a more powerful enemy