Genoa was one of several Italian maritime republics of this period (the best known being Venice). They used their very powerful navies to get rich in the Mediterranean, both because they were able to protect their merchants from piracy and because the larger European powers wanted to be friendly with them to have access to that naval power. Since they relied on sea power, their expansions focussed on grabbing useful ports rather than big swathes of land. They would often make agreements with the larger powers to set up a colony on the coast in their territory, which suited the larger power in question because it meant the republic’s ships would be bringing valuable goods to and from that port.

Theodoro is a bit of a historical oddity — it was the last Gothic state. As in the Germanic people that burned Rome down way back at the fall of the Western Empire, roughly a thousand years before this map. When they migrated into central and western Europe, some of them went to Ukraine and eventually into Crimea instead.

Crimea remained part of the Eastern Roman Empire up until the Fourth Crusade, in which France and Germany were supposedly going to go capture Jerusalem. The entire Fourth Crusade was a colossal shitshow which resulted in the crusaders partitioning the ERE instead, and the Crimean Goths basically just bounced between whoever happened to be the main power in the region for the next few hundred years. They managed to more or less maintain independence so long as they paid tribute to whoever was in charge that year (first one of the ERE’s successor states, then the Mongols, then a Mongol successor state, then a successor to that) until they were eventually conquered by the Ottomans a few decades after this map.