In Europe, Chinese OC has always been involved in heroin in a major way. From as early as the 70's, big time drug dealers from the Netherlands, France, Belgium...made frequent trips to Chinese restaurants in Amsterdam to get their heroin supply. The Cantonese 14K Triad had a lot of power in that business in the early 70's, but when law enforcement started to close in on the Cantonese, the Singapore-based Ah Kong came into play. The Ah Kong filled the void the 14K left had most of the Chinese heroin trade in Europe down from the mid 70's to the mid 80's. Although they were regarded as a Singapore-based Triad, its members had mostly roots in the Fujian province and family members who lived in for instance Mainland China and Malaysia were part of the Triad as well. Unlike the Hong Kong-based Triads, the Ah Kong has gone supposedly extinct, but they were an extremely powerful (and extremely vicious) Triad in their prime. They were a source of heroin for tons of traffickers throughout Europe and I'm willing to bet that most of the heroin in Brussels (which was a huge heroin market those days) could be traced back to them.

The Sicilian mafia was definitely involved in heroin as well, but in Europe I don't think they were as big as a source as the Chinese were in the 70's and 80's. Especially from the mid 70's to mid 80's with the Corleone-Palermo conflict, a lot of European traffickers did business with the Chinese instead. The USA is a different story.

The role of the Corsicans, even during the 70's and 80's, isn't to be underestimated either when it comes to the European heroin business. Even though the days of the "French Connection" were long gone, they were definitely still involved. They hid very well, but in the Brussels area there were dodgy characters from the Corsican underworld active. There are reports of a local criminal being sighted with one or two Corsicans at some cafe only to float up dead a week later in a place as far away as Le Havre.
I remember a story my uncle (who's from the Brussels region) told me that in the 70's he had some shady neighbor who he had seen talking with a few Corsicans repeatedly for some time. One day the guy packed his bags, left Brussels and supposedly moved to the South of France. A few weeks later they allegedly found his charred corpse with a bullet in the brain in the trunk of some burned-out car. Almost as if being sighted with a Corsican was an impending death sentence for mid-level criminals in those days.

The Colombian community was never as huge in Europe and even the USA as the Italian community is, but they definitely had their distribution cells. In Amsterdam in the late 70's and throughout the 80's there were Colombian criminals hiding who could provide the necessary. In the USA, especially on the East Coast, there were Colombian crime groups active in the wholesaling of cocaine. Lots of them in the Miami area and quite a few in New York as well.

In Europe the hashish business was under the control of the Dutch criminal organizations in the 70's and 80's. Even before Klaas Bruinsma you had Piet Clement and Henk Rommy ("The Black Cobra", a Surinamese guy, but his entourage was largely Dutch) who were behind enormous hashish transports. Piet Clement for instance used the Antwerp port to smuggle in tons of hashish in containers filled with entrails for the slaughterhouses.

The 70's and the 80's were shady as hell.