Sines and the island of Pessegueiro, were poles within an industrialized fishing industry which included salting fish. The Roman centres were thought to have been at Praça Tómas Ribeiro, as well as the area around Monte Chaos in Feteira Cima (although little explored archaeologically). In the fields of Quitéria, Carlos Tavares da Silva and Joaquina Soares (1981) investigated the remains of a 1st-century villa, where the remnants of cobblestone streets and a hypocaust were discovered. In 1961, José Miguel da Costa, during excavations around the Castle of Sines, discovered Roman "fishing factories", and a ceramics kiln to produce amphorae for salted fish, both dating back to the 1st and 2nd centuries. Sine's toponymy is also Roman in origin, but may refer to two terms (both applicable): the term sinus, which means bay; or an alternate meaning for curve, and may refer to the curvature of the Sines Cape, as seen from Monte Chãos. Middle Ages During the Middle Ages, the area of Sines was occupied by the Visigoths and later sacked by Moors. There are many more examples of Visigoth-era carved stones (7th century) throughout Sines. Evidence from an archaeological excavation of the Sines castle discovered that many of the walls of the old building were constructed from the rocks used in the construction of Roman-era monuments, such as a portion of a pedestal of a statue of Mars (which was assumed to have been part of a larger square in the Roman town before the construction of the basilica). The basilica itself likely existed on the site of the current Matriz Church, whose baptistery is of Visigothic origin. The Moors likely sacked the settlement in the 7th century; this marked a period of decline in the area, indicating a period when the ancient settlement was abandoned. Yet, although the few inhabitants lived in the zone, Moorish ships regularly patrolled the waters, until the 13th century, when Afonso III conquered the region. The area regained much of its importance at the beginning of the 8th century, when fishermen returned to the waters around Sines. Re-settlement along the coast was initiated by the Order of Santiago da Espada, who administered the lands under the reign of Afonso III. Sines obtained administrative autonomy from Santiago do Cacém on 24 November 1362, when Pedro I elevated Sines to the status of villa. He later preoccupied himself with the coastal defense of the region,