Get a grip, that area around St Enochs and even the four corners area of Argyle Street where the mcdonalds and pizza hut used to face each other has always been dodgy. Constantly junkies hanging around there in the 90s. I was assaulted there back in 2002 by a male and female junky in broad daylight and it took my friend screaming for help at a bunch of foreign european guys to split the fight up and protect me. Glasgow is not some quiet naice town that has suddenly been disrupted, it's just that the face of the gangs is looking more diverse now! Before it was all white gangs, now it's more of a mix.
No-one is importing gangs, some people are coming in either as individuals or with families and unfortunately a minority are getting caught up in criminal activity. The same as no-one born in scotland is deliberately raising gang members, but unfortunately some are involved in crime. When you think of it really it's not surprising what's happening. I said this would happen back in 2000 when they began arriving - considering the areas they are placed in asylum seekers they are being exposed to high poverty, high crime, low employment glasgow sub-culture that we all know has existed for a long time.
I know of middle class refugee or immigrant families that move to rough areas in the UK that were fine back in their home countries, but started struggling with their children due to the environment they were placed in. Back in the day African and Carribean families used to send their teens back to their countries if they were getting caught up in the wrong crowd here in London.
And not sure why you need to bring "sub-saharan' tribes into it? Glasgow has an aggressive gang culture centred around areas with each area having it's own young team. I remember in my town there were at least ten young teams, I'll never forget summer 2005 seeing 2 older teen guys jump out a car swinging machetes at my local park looking for the two main gang leaders in my area . Not to mention the sectarianism that literally led to deaths and weekly violence.
If anything the glasgow young teams are more tribal. These gangs you are talking about - many are from different countries in the same gang - it's about drugs and toxic masculinity. Same as with the white glasgow gangs. Your prejudice is showing because you can understand the phenomena of the many white Glasgow gangs without referring to 'clans' or 'tribes' but yet when it involves Black men you are quick to say tribes.