The Vietnamese community is the third largest minority in the Czech Republic. Most, if not all of the 7/11 shops in Prague are run by Vietnamese.
Prague also has excellent Vietnamese restaurants where you can enjoy the real, and very good pho or bo bun soup.
The Sapa Market is located south of the centre and it is some sort of a wholesale and retail market rolled into one. The other Vietnamese traders get their supplies from here.
You can even try your luck at bargaining here, you just might go away with something at a discount. At Sapa, you can find almost anything: clothing, (very) kitsch decorations, toys, but also ingredients for Vietnamese cuisine. In short, everything here is Vietnamese.
Don’t be put off by the look of this place: This giant market used to be a storage space, thus the look of everything seeming to be all cramped together. You can certainly find interesting stuff here.