The Vaccaei were an ancient tribe who settled in the Meseta Central of northern Hispania. According to Diodorus Siculus, they were the most cultured group of the Celtiberians, and Silius Italicus classed them as merchants and businessmen. Their existence is proved at least from the third century BC. Polybius relates, although he wasn't an eyewitness, the capture of the Vaccean cities of Helmantica (Salamanca) and Arbucala (Zamora) by Hannibal in 220 BC.
When the Vaccaei are considered a part of the Celtiberian people group, though the Vaccean civilization was the result of the a process of local evolution, importing elements from other cultures, whether by new additions of people or contacts with neighboring groups. Other more recent theories have suggested that the Vaccaei are a Celtic people, who arrived in successive waves in the area along with similar groups, becoming the first permanent inhabitants.
In the study of their settlements one finds elements of the Vaccean culture on top of the remains of earlier cultures. For example, at Pincia (modern-day Padilla de Duero (Valladolid)), there is evidence of a population from Eneolithic times until the Iron Age, when the Vaccean period arose.
The Vaccean culture extended through the center of the Meseta Norte, along both banks of the Douro River. Although its frontiers are difficult to pin down and shifted from time to time, it can be said to have occupied all of the province of Valladolid, and parts of León, Palencia, Burgos, Segovia, Salamanca y Zamora. At the time of the arrival of the Romans, the Cea and Esla rivers separated the Vaccaei from the Astures in the northeast, while a line traced between the Esla and the Pisuerga rivers was the border with the Cantabri. To the east, the Pisuerga and Arlanza rivers marked the frontier with the Turmogi, and a little farther south, the Arevaci were their neighbors and allies. On the south and southeast lay the Vettones in an area that is difficult to pin down, but corresponds roughly to the distribution of verracos around the highlands of Ávila and Salamanca and Aliste (Zamora), between them and the Lusitanians. It is probable that there was contact with the Lusitanians to the west of Zamora.