Rivia is both a country and a city(Capital). There are multiple cities in Rivia.
Was there any precedence of having a city/country as "part of your name" in medieval times for individuals that did not directly rule over the said city/region? If so, how would one go about getting this title?
The most obvious example that springs to mind is the legion of medieval clerics, academics and writers who adopt that naming convention; individuals like Alcuin of York, William of Malmesbury, Regino of Prüm, Geoffrey of Monmouth, Gerald of Wales etc. Gerald is technically Gerald de Barri, which is a titled name, but he adopted the pseudonym Giraldus Cambrensis for his writings.