In the Iron Age, Sepúlveda emerges as a Celtic castro from the tribe of the Arévacos.
In Roman times, the remains found in Duratón in 1791 and 1949 show it with a broad life, related to the exterior, and a municipal statute. From the Visigothic era is the Necropolis excavated in Duratón (aggregate town or neighborhood of Sepúlveda), with 666 graves with almost entirely Germanic trousseaux. The first historical mention of the town of Sepúlveda appears in the "Chronicle of Alfonso III", as one of the places that were depopulated in the raids of Alfonso I, although there was a rural population in its environment.
Its repopulation by Fernán González, in the year 940, represented a bold advance towards the south, beyond the Duero. The Abbot of Arlanza, Fray Gonzalo de Arredondo, tells us his heroic legend, with the fight between the Count of Castile and the warden Moro Abubad, to whom Fernán González cut his head, which today is sculpted on the facade of a of the coats of arms of the Villa, called precisely "La Casa del Moro". Almanzor failed in his attempt to win the Villa in the 979 year, but 984 or 986 did it, and Sancho García, grandson of Fernán González, returned in the year 1010.
The Fuero de Sepúlveda
The same Count of Castile, Fernán González, to attract people who defied the dangerousness of this frontier place, granted the town of Sepúlveda its Charter, which his successors were confirming. His oldest text that has reached us, of the year 1076, is the Latin of Alfonso VI, his definitive repoblador. The Fuero de Sepúlveda embodied the Law in Extremadura Castellana, and around it a more extensive legal body was formed, in Spanish now, which was codified in the 1300 year. Its diffusion was very extensive, being granted to Saragossa and Teruel and, from Uclés, to many populations of the Order of Santiago. The term delimited by the Charter is that of the Community of Villa and Tierra de Sepúlveda, which still exists, and that includes 39 towns and more than 11.000 inhabitants.
In the year 1111, in the Field of the Thorn or Candespina, today Fresno of Cantespino, Alfonso I of Aragon and the count Enrique of Portugal won to the woman of first, Dª Urraca. The event was transcendent for Portuguese independence, and as a consequence of it, Sepúlveda was for some time under Aragon rule. In the year 1468 the Jews are expelled from the Villa; and in 1472 the sovereignty of the future Catholic Monarchs is recognized, preventing twice and forcibly the entry of Henry IV into the municipality. During the War of Independence, the Empecinado made incursions into the area, having its barracks in the caves of El Duraton Canyon.