The picture is the museum of Nan-Yue. It is in Chinese, not Vietnamese.
The picture is the relic of Nan-Yue in Guangzhou.
Thanks for the picture of the question. Guangdong and Vietnam were within the Nan-Yue, and the political and culture center was in Guangzhou. It means that It was Vietnam belonged to Guangdong, not the other way around.
Zhao Tuo, the king of Nan-Yue, was the governor set by Qin Shihuang. When Qin dynasty ended and Han dynasty established, Zhao Tuo did not join Han immediately. It is like Taiwan does not joint Mainland immediately. Zhao Tuo joint Han eventually. Nan-yue belonged to Qin Dynasty first, in between for a period of time, then joint Han Dynasty.
Vietnam has long been part of China until French annexed it from China.
This status is for local Cantonese people who defend Chinese territory against French invasion in Guangdong Province.