The thing is, the criminals do tend, and when I say "tend to" I mean "as far as I can tell, always are, although obviously just because I've not seen a counter example doesn't mean one doesn't exist" always be from similar ethnic groups.
You've heard of the Italian Mafia? A criminal organization where ethnicity was literally a criteria for admission? Or, while not criminal, Jewish diamond merchants? Having a specific ethnic group specialize in a certain type of commercial activity isn't new.
When that activity is trafficking drugs from Morocco, against the wishes of the local state, it's not surprising that the organization is largely composed of people who happen to share a common language, culture and ethnicity with Morroco.
And if you're wondering why Morocco, well that's where all the hashish is grown.
You've possibly been to "Chinatown" in a large city (say NYC). Now remplace east Asian immigration with North Africa immigration, replace the stereotypical restaurants and dry cleaners with drug dealing, and you have north Marseille.
This unfortunate fact actually drives a lot of the racism. If you ignore it because it sounds racist well... The problem will remain, refusing to accept that there currently is an ethnic group that dominates illegal drug trafficking in a certain place, due to ties with the source of the drug doesn't make it any less true.
Similarly, of you're smuggling cocaine into the US, speaking Spanish is a really good trait to have. Because the country that produces most of the cocaine speaks that language.