The town's origins date back to the fifth century BC, because this is when a
Celtiberian settlement known as
Bursau or
Bursao had existed near the current ruins of the castle. After the
Roman conquest (first century BC) also the slopes of the hill were populated, though the town started to expand significantly only after the
Muslim conquest in the eighth century AD. In the twelfth century it was conquered by the Christians from the north, and in the fifteenth/16th centuries it was converted into a military fortress against the
Castillan invasions, but at the same time received much of its historical architectural heritage, with numerous churches and palaces. It received the title of "city" by King
Alfonso V of Aragon in 1438. During the reign of the
Catholic Monarchs, the Jews, forming an important part of the Borjan community, were
expelled. The
House of Borgia, which rose to prominence during the Italian
Renaissance, originated in Borja and their name was a variant of the town's name. However, since at the time when they lived in Borja they were not yet especially prominent, their earlier history remains largely unknown. Borja existed through a period of recession and plagues in the seventeenth and eighteenth centuries. It recovered economically starting from the nineteenth century, when a railway connecting the city to
Cortes, in
Navarre, was inaugurated. In the twentieth century agriculture, traditionally the mainstay of Borja's economy, started to lose its importance, and, without a consistent industrial base, the city lost economical and political importance in the area: much of the population therefore emigrated to other more developed areas. The industrial sector is intended to be boosted by businesses being attracted to the ongoing development "Polígono Industrial Barbalanca", the Barbalanca Industrial Estate. ==Demographics==