The Roman sources previous to the conquest take issue with a city of Celtic origin, capital of the Vacceo people, in the hillsides of the hill of Malpique and Macarefe. The Vacceos were extended in the lands that today are León, Zamora, Salamanca and Valladolid.

Roman accession (29 a.C. - 19 d. C.)

Floro, Orosio and other Roman chroniclers, upon reporting the war of August against cántabros and astures, refer that among the peoples that were maintained to the margin of the contest was found the vacceos, and here seated the legacy Carisio their winter quarters, before the conquest of Lancia. During the imperial-time, Valderas it was one of the main - " stationes " - of the route that was communicating Astorga with Zaragoza, whose name was Brigaeco or Brigecum and was located in the field called today Altafría.

From Brigecum to Castro Mazaref. First Valderas (Century X)  

During the visigothic period, the city was a defensive enclave against the suevos from Galicia and the cántabros from the north of León and Palencia. During the Moslem invasion of the 711, suffers a backspace in its population, but is not aborted totally. After the Reconquest is again fortified and appears mentioned as Castro Mazarefe, name of an spanish-moslem repopulator. During the reign of "Urraca de León" it's begun to call Valderas:
"...In Val de Heras.. discurrente flumen Ceia, sub Kastro Maçarefe...".

The siege of the Duke of Lancaster (Century XIV)

Under the señorío of the Osorio family, Valderas took split by the infant Enrique of Trástamara in the civil war of 1366 to 1369. The city was fenced by the legitimate Sir king Pedro and resisted the siege, but the Duke of Lancaster, son-in-law of the deceased king Sir Pedro, after invading Castilla cames against Valderas, that it was leaved, after burning its víveres, this fact figures in its shield. This attitude deserved that the king Juan I of Castilla conceded to village tithes and you arbitrate actual and privileges.

Centuries XVI and XVII

During the revolt of the Comuneros, during the reign of Carlos I, Valderas took split by the monarch, what report many advantages for the village that was converted in one of the most important markets of the Kingdom and in headquarters of the Greater Advance of the Leonese Kingdom. These facts contributed even more to the Valderas growing and brought new contributions of population of French and Flemish merchants.

Contemporary Age

With Carlos II is extinguished the legitimate dynasty of the Austrias and the Spanish throne is disputed by Borbones and Habsburgos. Valderas it is inclined by Felipe of Anjou, that would be king with the name of Felipe V. Almost a century after, Napoleón was sheltered in Valderas in his advances by the Peninsula.

During the centuries XIX and XX, Valderas did not return to suffer the acountings of a war, not even during the civil war from 1936; however Valderas it has not recovered the brilliant economic and cultural prosperity the one which enjoyed during the medieval and modern centuries.