It is unclear when humans settled Castelo de Vide, although archaeologists suggest the decision came from the morphology of the soil and from a territorial strategy to occupy and conquer land. The establishment of a fortification helped fix a new population to the territory and, at the same, functioned as a strategic border fortress. The 14th-century
Synagogue of Castelo de Vide in Santa Maria da Devesa still stands, and despite
Portugal's expulsion of Jews in 1496 was used by
Marranos as a religious sanctuary and school until the 16th century. Today it houses a small museum dedicated to Castelo de Vide's historical Jewish community. Many of the perceptions of the town came from the 16th century drawings of Duarte d'Armas. At that time the settlement was dedicated to agriculture (cultivation of wine grapes, cotton, olives, fruits, and cereals) and raising cattle, while watermills were constructed along the ravines in Vide and Nisa. At the beginning of the 16th century, toward the end of King
John III's reign, the wool industry became important in the region. This resulted in Castelo de Vide's inhabitants being referred to as
Cardadores ("
carders"). Castelo de Vide had 885 inhabitants in 1527, rising to 1,400 by 1572 and 1,600 by 1603; this population growth resulted from growth in agricultural production, the textile industry, and commerce with Spain. The new
foral ("charter"), issued by King
Manuel I in 1512 established new laws for public spaces and set the town's boundaries. ==Geography==