Vietnam was land that developed a strong cultural identity, and was extremely hard for conquerors to conquer. China first attempted in the 200's B.C. but did not establish a foothold in the region until 111 B.C.
North blew all of its money on slaves so instead of a bunch of white people close together in the state you had hella plantations and slaves that were spread out
July 28, 1868... I hope this helps :D