Graeko-latin authors dating back two millennium left written testimony that the current territory of the Autonomous Community of the Basque Country was inhabited by three different communities, namely: "várdulos", "caristios" and "autrigones"; the latter settled between the rivers Nervión and Asón, where the historical region of the Encartaciones is located and Santurtzi always formed part of the same.
When the Middle Ages commenced, after the collapse of the Visigothic state, the Astur king, Alfonso I, repopulated the lands of Sopuerta and Carranza with people from the valleys of the Duero and Ebro rivers, who introduced vine and cereal crops, together with Christian faith; the first testimony of the temple of San Jorge (Sancti Georgi), which dates back to 1075, is reflected in a document from the Monastery of San Salvador de Oña, which mentions the Monastery of San Jorge in Somorrostro.
As from the 14th century, and coinciding with the founding of towns by the great territorial lords, the space was organized: the seven town councils of Somorrostro formed two republics within the area of the Encartaciones in Biscay, which were both represented at the Council of Avellaneda. Santurtzi, Sestao and the Valle de Trápaga made up the entity of the Three Councils in the Valley of Somorrostro until the 19th century.
Since the end of the 2nd Carlist War, the liberalization of the economy led to a radical transformation of the region. This was also reflected at administrative level, with the disintegration of the old Council of Santurce in 1901, which was divided into Santurce Ortuella and Santurce Antiguo.