Human presence in the area of Almada dates to the end of the Neolithic period about 5000 years ago; archeological excavations performed in the municipality suggest that non-sedentary nomadic tribes may have occupied this location sporadically. The gradual development of settlement here made its greatest advance with the coming of Islamic civilization, when Muslims constructed a fort at Almada to defend and monitor the entrance to the Tagus River. Lying across the river from Lisbon, the area of Almada was a crossroads for a succession of various peoples who traded along the Tagus, including Phoenicians, Romans and Moors.
As one of the principal Arab military bases along the southern margin of the Tagus, Almada was conquered by the Christian forces of Afonso I with the aid of EnglishCrusaders in 1147. Alongside these Christians there lived many free Moors and Jews, under the royal protection guaranteed them by Afonso I in the charter of 1170 (which applied to all the former Moorish strongholds at Lisbon, Almada, Palmela and Alcácer).
Almada received a foral from King Sancho Iin 1190, although it came at a price: Miramolim Jacub-Abu-Jassuf, son of the Moorish leader who had laid siege to Santarém in 1171, was angered by the Christian victories and gathered a large army. He boldly attacked in the north, conquering Alcácer do Sal and Silves, while forcing the residents of Almada, Palmela and other towns along the Tagus into hiding. It would be some time after the death of Sancho before this region would be restored to Portuguese control.
When this event occurred with the success of the Reconquista in driving the Muslims out, the Order of Santiago, a donatorio of Almada after 28 October 1186, had an important role in the territory (especially between the Tagus and Sado Rivers). In this role, it facilitated the repopulation of acquired territories and was the beneficiary of the various local economies