Cambodia-Laos-Myanmar region definitely is a major heroin source. Seems like that racket is mostly being exploited by Chinese and to a lesser extent Vietnamese OCG's.
I heard about the Vietnamese drug-related murders in Philly a few years ago. Some of the Vietnamese gangs seem to have bigger, more organized networks. Some of them make quite a bit of money from counterfeiting, heroin, pot grow houses...

Cambodian gangs I'm familiar with Tiny Rascal and a lot of the Blood and Crip gangs they emulate, but it doesn't seem to go much beyond low level drug selling and stealing from their own.

Gambling is huge in Vietnam and China. When I was in China almost every restaurant and apartment block had a room where they were gambling. They were always playing some card game, but I could never really figure out what it was. Funny thing is when some of the Chinese guys were playing the cards some of them had another online gambling game open on their smartphone and they were doing both at the same time lmao

I heard that Mexican and South American/Caribbean dope as well as the East Asian dope that's being pushed these days is utter garbage. Smack users were better off with the Sicilian stuff