Military religious Order in Spain, founded in the Kingdom of León, c.1175, as the Order of San Julián de Pereiro, which was a monastery close to Portugal and WSW of Salamanca. The Order was linked at first with that of Calatrava. Its headquarters later moved to Trujillo, east of Cáceres, in 1188 and finally in 1218 to Alcántara, which had been taken by Alfonso IX four years earlier. Alcántara stands on the River Tajo (Tagus) some way above where it forms the border between Spain and Portugal. Above the town today is the immense Alcántara reservoir on the Tajo and its tributaries.
The Order held substantial territories in Extremadura: in the northwest, the lands on the borders of Portugal from San Vicente in the south to Valverde del Fresno and Santibáñez in the north, and in the southeast, the lands contained within the great arc formed by the River Zujar, a tributary of the Guadiana. In Andalucía the Order acquired territory southeast of Seville, around Cote and Morón.
The Order was usually subject to royal influence and eventually the Grand Mastership became tied up with the Crown after Ferdinand II of Aragon, the husband of Queen Isabella, had been elected Grand Master in 1494.