Vietnam was indeed part of China for a thousand years. It is time for China to wage war on Vietnam to reclaim lost Chinese territory.
History of Vietnam - Wikipedia, the free encyclopedia
"The history of Vietnam begins over 2,700 years ago.[citation needed] By far Vietnam's most important historical international relationship has been with China.[1] Vietnam's prehistory includes a legend about a kingdom known as Van Lang (27872858 BC) that included what is now China's Guangxi Autonomous Region and Guangdon province, as well as the northern part of Vietnam.[2]
Later, successive dynasties based in China ruled Vietnam directly for most of the period from 207 BC until 938 when Vietnam regained its independence.[2] Vietnam remained a tributary state to its larger neighbor China for much of its history but repelled invasions by the Chinese as well as three invasions by the Mongols between 1255 and 1285.[3] Emperor Trần Nhân Tông later diplomatically submitted Vietnam to a tributary of the Yuan to avoid further conflicts. The independent period temporarily ended in the middle to late 19th century, when the country was colonized by France (see French Indochina)."