When i was a kid in 2000s, Korean mutinationals & culture not that well known. The Korean mutinationals were investing in Vietnam but not as much as they do now. If you asked Vietnamese in the 2000s about Korean firms, Daewoo & Huyndai were probably more well known among Viets than Samsung. Also the 2000s was the era where Japanese electronics basically flooded the market (Toshiba, Panasonic, etc). Additionally Japanese manga (doraemon) and anime were becoming popular (and still are today). Hong Kong at that time was still free and produced tv dramas that Viets enjoyed.
Somewhere in the 2010s, the Vietnamese market for electronic products has become split between Japanese ones and Korean ones. Kpop started to gain more popularity around the world and K dramas were basically free of charge and got televised all the times. At that time i didnt understand why Koreans were so eager to export their culture to us but now i understand. There are certain products that Koreans produce but have no buyers from the Western world & Japan. Beauty products are one of them. Koreans want more people to have the same beauty standards as theirs. Aside from their beauty products, another type of Korean products that appear in K dramas but have no market in the Western world & Japan is Korean foodstuffs (noodles, seasonings, ect...). Koreans want to influence our cuisine in the same way the French did to ours (banh mi, cafe, etc...). To me, South Korea did very well to become an industrial power but at this point in time, South Korea has ran out of customers for its products.
Now even though Japanese brands are not dominating Viet market like they used to, The Japs have evolved their business strategy and become smarter in exporting their culture. Viet public highschools now have classes that are tailored for Viet students who plan to study in Japanese universities later on. Japanese barbecue & sushi restaurants, convenience store franchises are almost everywhere in big cities. Unlike the Koreans who like to do things that attract maximum attention (this includes both North & South Koreans), the Japanese prefer to do things in a more subtle way.
