I have read both your arguments and opinions.
I think the main divergence is the misplacement of hsitory.
Any country was established gradually in ancient. Firstly based on bloodline, they formed gen/clans, clan+clan formed group, group+group formed tribe. Tribe and tribe formed tribes union, which is the embyro of country. Country is a political concept, it must has governing machine and rules, such as leader, organizations, officials, army, ranks, even laws...Otherwise, the tribes or groups were easily assimilated by a country. We can observe the whole world, by throughing those stages, the formed country and ethnicity are very stable nowadays. The longer, the stabler.
Later country and country would have wars and annexion, forced assimilation, even holocaust incident. At same time, country would aslo has riots, collapse, divide into several parts.
Back to discussion,
@Fattyacids @Rechoice
China and Vietnam are too close in distance and geographical. Maybe human had connected with each other before the gen, group, tribe consciousness was established. ( China and India have Himalaya the obvious block, America and Britain have Atlantic ocean the distance. So their histotical connections are very clear. )
If Chinese and Vietnamese really want to solve these historical divergence, they (people, esp. professors from both country) must discuss and wirte ONE history together under all kind of evidence, proofs.
The historical connection between two nations
after 960's A.D are very clear. Because after Vietnam's independence, most Chinese and Vietnamese dynastys accepted and treated each other as different country. The divergence so far is focusing on history before 960's A.D, especially when Qin dynasty in 214 B.C set up county there, if the local people had already set up country or not. (By the way, we talk about Sino-Viet historical story, which are mainly about northern Vietnam. After 960's Vietnam developed toward southern and western, that is Vietnam's own history. )