The origin of its name sangalhos, which refers to a unit of measure, as hypothesized by Joaquim de Silveira, came from the cult of São Galo (Sanctus Gallus).

The hamlet of Sangalhos, appropriated by Count Sesnando, first and illustrious governor of Coimbra, was donated to the Church (and Hospital) of Mirleos, founded in the city of Mondego.

During this era, the parish consisted of two metropoles: its seat, Sangalhos do Paço (et alio Sancto Galios), and Sangalhos da Igreja (Sancto Galios), in addition to the localities of Saima, Sá, Casal da Rua and Avelãs de Caminho The great monasteries of Lorvão, Vacariça, and Santa Clara de Coimbra dominated the activities in the region of the Bairrada.

Santa Clara de Coimbra, founded by nun Mor Dias at the beginning of the 14th century, in who the patronage and lands of Sangalhos was entrusted after 1338.

As a result, Amoreira da Gândara, Fogueira, Paraimo and São João, all mentioned in the Manuelino foral, were increasingly active hamlets.

Sangelhos became a regional military outpost, whose territory included many of the local parishes of the modern municipalities of Anadia, Oliveira do Bairro and Águeda.

After the Liberal Wars (1820–1835), the donation to the monastery of Santa Clara de Coimbra was annulled and the municipalities of Sangalhos and Avelãs do Caminho (which became an independent parish within Anadia) became extinct.

Its inhabitants built many prosperous businesses that influenced the growth and development of the community, including pioneering bicycle production in Portugal and ceramics industry.