The society in the Byzantine Empire (4th-15th century CE) was dominated by the imperial family and the male aristocracy but there were opportunities for social advancement thanks to wars, population movements, imperial gifts of lands and titles, and intermarriage. The majority of the lower classes would have followed the profession of their parents, but inheritance, the accumulation of wealth, and a lack of any formal prohibition for one class to move to another did at least offer a small possibility for a person to better their social position. In Constantinople and other cities, foreign merchants, mercenaries, refugees, travellers, and pilgrims were constantly passing through or establishing themselves permanently within the empire so that Byzantium became famously cosmopolitan; a fact noted by contemporary visitors who recorded their astonishment at the diversity of the society they visited.
True, post WW2 Japans economy boomed and especially in that time they became a world economic power and today they are still one of the strongest economies in Asia.
