Um, that is essentially what happened about 100 years ago. A few differences though... The europeans brought along lots of armed guards and demanded China's laws didn't apply to them. Obviously, there was some friction.
Yes, among other locations (Hong Kong, Canton, Amoy, Shanghai, etc.). I was describing the various "treaty ports" that were established following the Opium Wars, which were essentially a series of wars fought by the west to allow the import of illegal drugs into China. The major western powers forced China into providing land and extra-territorial rights to westerners in China.
The Chinese still remember this era quite vividly and describe it as the "Century of Humiliation".