Espalmador, an islet between Ibiza and Formentera, was an important port of transit in antiquity, given its strategic location on western Mediterranean trade routes.
The period of scant historical knowledge that opens with the Vandal and Byzantine invasions of the Illes Balears in the fifth and sixth centuries ends with the documentation of the Moorish presence, as confirmed by tombstones dating from the first years of the second millennium A.D. When the Catalan troops of Guillem de Montgrí conquered the Pitiusas in 1235, Formentera was still inhabited by Saracens, as recalled by the Llibre dels Feyts. The attempt to establish a permanent population on Formentera failed; the harsh conditions on the island and the insecurity caused by Berber incursions brought an end, towards the end of the fourteenth century, to what is called the first repopulation.
Three centuries had to pass before the people of Ibiza decided, in 1697, to repopulate Formentera. They began by erecting the fortified church of Sant Francesc Xavier, which gives its name to the island's principal town, and which offered safety to the people of Formentera for decades. Defence and watchtowers along the coast completed the security network and made the second repopulation definitive.
Around the middle of the eighteenth century
Formentera's population was four hundred, at the end of the previous
century nearly two thousand, and now it has nearly seven thousand.