The Bendidia was an ancient Athenian festival celebrating the Thracian goddess Bendis. It was celebrated on the 19th day of the month of Thargelion (late May, in the Gregorian calendar), and was introduced in 429 BC. The festival took place in the Piraeus. It was rare for ancient Athens to permit foreign residents of the city to worship their own gods; the cult of Bendis and the Bendidia is one of a few exceptions, driven by the strategic importance of Thrace to Athens at the beginning of the Peloponnesian War.