How do we explain Zevran's accent then? Spain has fish markets and great fish soup.
It's really more so Italy because of how Antiva is run. Italy, or more specifically Italian city states. Italy up to the nineteenth century defied centralized government for the most part, with the landmass of modern Italy divided into city states run by powerful merchant families, and the Papal States, under the direct rule of the Pope. There a reason "The Merchant of Venice" is a big thing by Shakespeare - Venecian merchant consortiums, together with other wealthy psuedo-dynasties, exerted far greater power over Europe and Eurasia than one would ordinarily expect from such a small territory, land wise.
Getting back to Dragon Age, according to the wiki and Zevran, Antiva is run by similar powerful merchant princes - Prince Azrin, etc. Each prince fields their own army and uses the threat of a third-party force to keep outsiders wary - for the real-life Italian merchants, it was the threat of hiring large mercenary armies, for Antiva, the Crows. Machiavelli himself wrote about the dangers of putting too much trust in the hands of hired mercenaries - they were that popular in his time. Of course Italian city states, just like Antiva, were conquered by outside powers occasionally nonetheless - see the history of HRE Frederick I Barbarossa for my favourite story, where the man himself was so irritated at the lack of cooperation from the Pope he crowned his own "Anti-Pope" and sacked his way through the Italian Peninsula.