The origin of the name, Pisa, is a mystery. While the origin of the city had remained unknown for centuries, the Pelasgi, the Greeks, the Etruscans, and the Ligurians had variously been proposed as founders of the city (for example, a colony of the ancient city of Pisa, Greece). Archaeological remains from the 5th century BC confirmed the existence of a city at the sea, trading with Greeks and Gauls. The presence of an Etruscan necropolis, discovered during excavations in the Arena Garibaldi in 1991, confirmed its Etruscan origins. Ancient Roman authors referred to Pisa as an old city. Strabo referred Pisa's origins to the mythical Nestor, king of Pylos, after the fall of Troy. Virgil, in his Aeneid, states that Pisa was already a great center by the times described; the settlers from the Alpheus coast have been credited with the founding of the city in the 'Etruscan lands'. The Virgilian commentator Servius wrote that the Teuti, or Pelops, the king of the Pisaeans, founded the town thirteen centuries before the start of the common era.