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Medieval Barcelona

The city was conquered by the Visigoths in the early 5th century, becoming for a few years the capital of all Hispania. After being conquered by the Umayyads in the early 8th century, it was conquered after a siege in 801 by Charlemagne 's son Louis, who made Barcelona the seat of the Carolingian " Hispanic March " (Marca Hispanica), a buffer zone ruled by the Count of Barcelona.

The Counts of Barcelona became increasingly independent and expanded their territory to include much of modern Catalonia, although in 985, Barcelona was sacked by the army of Almanzor. The sack was so traumatic that most of Barcelona's population was either killed or enslaved. In 1137, Aragon and the County of Barcelona merged in dynastic union by the marriage of Ramon Berenguer IV and Petronilla of Aragon, their titles finally borne by only one person when their son Alfonso II of Aragon ascended to the throne in 1162. His territories were later to be known as the Crown of Aragon, which conquered many overseas possessions and ruled the western Mediterranean Sea with outlying territories in Naples and Sicily and as far as Athens in the 13th century.

Barcelona was the leading slave trade centre of the Crown of Aragon up until the 15th century, when it was eclipsed by Valencia. It initially fed from eastern and Balkan slave stock later drawing from a Maghribian and, ultimately, Subsaharan pool of slaves.

The Bank or Taula de canvi de Barcelona, often viewed as the oldest public bank in Europe, was established by the city magistrates in 1401. It originated from necessities of the state, as did the Bank of Venice (1402) and the Bank of Genoa (1407).