The Centuries of Silence

The 5th century AD found Eleusis Christian. There is no evidence for the previous period, except for some references in the writings of the Church Fathers denouncing the "orgies of the initiates."
The layout of the Church of St. Zacharias (similar to other buildings in Asia Minor) reveals communication with other Christian centers.
The basilica of Saint Zacharias dates back to the 5th century.
Pirate raids began in the early 7th century. After the conquest of Crete by the Arabs (825 AD), around 881, the most destructive raid took place on the coasts of the western Peloponnese, western Attica, and the Saronic Islands. The inhabitants fled inland and arrived in safer cities, such as Thebes and Athens.
The Arab pirates were succeeded by others—Muslims, Genoese, Normans—and so the return of the inhabitants was impossible.
In the 13th century, Athens and the whole of Attica were occupied by Othon de la Roche on behalf of the King of Thessaloniki, until 1311.
On March 11, 1311, the Franks were replaced by the Catalans.
In 1333, the Turkish fleet appeared for the first time in the Gulf of Eleusis, where it was confronted by Byzantine and Venetian forces.
In 1388, when Attica fell to the Florentine house of Acciaioli, Eleusis remained uninhabited.
At exactly the same time, the Arvanites completed their penetration into Greece, until 1333 when they declared their allegiance to the Byzantine emperor. New Arvanite groups settled around the middle of the 14th century and the beginning of the 15th century. Due to raids, they and the few locals withdrew inland to Kountoura, choosing the land where they had lived for centuries, practicing agriculture and pastoralism. It was only towards the end of the Ottoman occupation that the Kountouriotes Arvanites moved to Mandra, Magoula, and Eleusis, having already assimilated with the other inhabitants of Attica.
In 1458, Attica was definitively conquered by the Turks. In the same year, the first privileges were granted to the inhabitants of the region, and the kazas (district) of Athens was created, which included the region of Eleusis but from Eleusis to Mazi and Perachora.
By order of 1680, the Turks renewed the property titles of the Kountouriotes, who thus continued to live in the area.
The consolidation of Turkish rule, but mainly the reduction in piracy, opened the way for the Kountouriotes to move to the coastal area.
In the 18th century, the population remained stable, despite some growth in the port of Eleusis. In 1798, the population is reported to have reached 200 (Olivier). However, the surrounding areas resemble small towns: Mazi had 30 houses, Kountoura 300 houses, and Vilia 150.
In 1815, Pouqueville reported that he found forty families in Eleusis, who cultivated the plain, and that small ships arrived at the port to load olives, resin, wine, and a little wheat. A han, a customs house, and a few shops were the only buildings. Kountoura was home to 300 families, with a total of 2,100 inhabitants, 730 of whom were armed.