Aarakocra in the Grey Dragon world are only found in and about their new state Aa. The three settlements mentioned on the map are meeting centers, not actual cities. The northernmost one houses their Wizardlander Ambassador, and it is the center of trade with Horia.
The central settlement is rumored to be a religious center and it is only accessible through air.
The southern settlement is the center of the “southern and eastern expanse”. Aarakocra seem to believe that anything east and south (in flight range) is their rightful hunting land. They do not enforce it though as they have a very limited adoption of real estate rules and land conquest.
The entire Aa civilization has appeared out of thin air a few years before the first open Gates. They call themselves refugees but refuse to discuss any further information in the matter. Some outsiders believe that they were favored by the Grey Dragon, and brought to the World in a secret first Gate.