Popular Card Games by Country?

My brothers are going on an extended back-packing trip starting in India and going eastwards across Asia this summer, and I'm planning on sending them off with a couple decks of international playing cards and rules for card games that are commonly played.

Games I'm aware of so far include Big Two (and numerous variants) in China, Tien Len in Vietnam, and Truf in Indonesia. Pagat's National and Regional list of card games has been a great jumping off point, but I'd like to hear more direct information and opinions from anyone living in or having visited Asia.

What card games are well known and can be played with only one to two decks of cards? Redditors from other countries, feel free to chime in as well, as I'm planning on including other, general card games!