I'm sorry, but Vietnam is not an East Asian country.

Every time I see Vietnamese netizens emphasizing how similar their culture is to that of China, Japan, and Korea, I feel embarrassed and heartbroken. Because Vietnam is, after all, a Southeast Asian country. The ancestors of the Vietnamese people were indigenous, their language does not belong to the Sino-Tibetan language family, and their physical appearance differs from that of East Asians. And if you observe Japanese and Koreans online, they wouldn't say they are very similar to China, much less promote any concept of a Sinosphere. Vietnam was historically colonized by China for a long period, but this does not make Vietnam an East Asian country; that is a disgrace.