The history of the settlement in the Soajo region is old. The Rupestre Sanctuary of Gião - Serra do Soajo - and the countless Antas and Mamoas are some of the countless documentary landmarks. The first written document dates from 950 and refers to the sharing of assets between Countess Mumadona Dias and her descendants.

The Municipality of Soajo is mentioned in the General Inquiries of 1258, ordered by D. Afonso III. Also the Rol dos Besteiros do Couto, dating from the reign of D. Afonso III or D. Dinis, makes reference to the Julgado de Soajo. Still in 1283, at the D. Dinis Chancellery (1279-1325) in Torre do Tombo, there is the document regarding the dispute solution that occurred in the Municipality of Soajo.

In 1388, at the beginning of the reign of D. João I (1383-1433), the abbot of the Parish of Ermelo, then Municipality of Soajo, addressed the king stating: «The Monastery of Ermelo was built by D. Teresa, at the Soajo Court. In 1401, D. João I interdicted the nobles, in obedience to what came from before, to live in the land and in the Soajo Court, at the request of the councilors of the Soajo City Council.

In 1456, the Municipality of Soajo took a position on matters relating to the taxation of goods sold at the Valdevez fair.

According to the historical archives of the village of Soajo, its foundation dates back to the 1st century, but it was only in October 1514 that it obtained the Foral de D. Manuel I (1495-1521). At that time, the Municipality of Soajo covered the Parishes of Ermelo and Gavieira.

In 1657, during the Restoration wars, the people of the Municipality of Soajo took an active part, next to the Lindoso Castle, fighting heroically for the Restoration of Portugal's second independence, according to a document published in Subsidies for the History of Terra da Nóbrega and Ponte da Barca, by Professor Avelino de Jesus Costa.