A beautiful small town: that is how the Jew Benjamín de Tudela perceived the city of Barcelona on a trip starting at Tudela, his birth place, taking him all across the Mediterranean to the East. It was in 1166 and although Barcelona was a secondary centre, according to Tudela, it was much frequented by Mediterranean traders. He wouldn't have recognised it a hundred years later when Barcelona had turned into a major trading market place, from where most of the surplus in agricultural and manufactured production was distributed within the Catalan territory. It was also the entry point for large quantities of both luxury items and basic products imported by the Crown of Aragon. It had succeeded in increasing its commercial activity spaces considerably and creating a complex exchange system in which big international centres of commerce would participate, such as Mallorca and Valencia as well as other smaller towns that relied on artisan activity and which were brought together by an efficient internal commerce network. Such is the basis for the Catalan expansion in the early Middle Ages.