First established in 1849, the French Concession was the French "third" of Shanghai, governed in cooperation with, but completely independent of, the International Settlement.
The French Concession was generally considered to be the most fashionable of all locations in Shanghai. It was the home of the most valuable real-estate and the most definitively European (specifically French) culture in all of Shanghai - perhaps (with the exception of the most Anglicized areas of Hong Kong) in all of China. It had many of the trappings typical of French colonial civilization - a French style government, a strong Roman Catholic establishment, and a distinctive French continental architectural style.
It was also, incidentally, rank with corruption, and was widely regarded as the number one location for high class Opium dens and Brothels. The crime rate in the French Concession was actually quite low, and these were specifically maintained with an eye toward attracting foreign tourists and the residents of the other sectors of the city. In particular, the recently developed "Heroin" was widely developed in and exported from the French Concession, much to the chagrin of the Chinese and the Shanghai Municipal Council.
Nevertheless, there were internal problems aplenty. Corruption could be found at virtually all levels, including the government of the Concession, the police force, and (sadly) the Church itself. There were honest men and women in all three of these sectors of French society in Shanghai, but they were generally outnumbered and outgunned. Such would be reformers were frequently found dead, or were effectively marginalized by their peers.
Ironically, despite these problems, the Concession was remarkably egalitarian. It was quite Liberal by the standards of the time, and included among its residents many well educated Black citizens, as well as numerous Chinese natives who had worked their way up in the system. A number of affluent Women were also active. Some of the most notable reformers - and corruptors - in the Concession, could be found within these three groups.