Merchants thronged to the large cities that were growing up around the castles at Edo (population already 1 million in the 18th century), Osaka (400,000), and Nagoya and Kanazawa (each 100,000) all huge in comparison with European cities of the time.
Large cities like Edo, Osaka, and Nagoya and Kanazawa, which were huge in comparison with European cities of the time, brought to them many merchants, 
Cities huge in comparison with European cities at the time, did not get a lot of merchants thronging to them.