I think it is multi-fold:
Before Somalis arrived the scene in the early 90s (some in late eighties, but not many, and I am not discounting Seamen and their families, if small in number, in Liverpool, Cardiff, East London etc), there were only West Indies i.e. Jamaicans etc, then Somalis took over, and I think after the Indians, who technically know own brown Britain, so far as small businesses are concerned, no other ethnic group has established themselves in the UK as the Somalis. I am going by memory, and what I observe when I go back to visit family, and friends round Christmas.
In my past few trips to London, I have not seen many West Indians, as their traditional neighbourhoods i.e. Brixton, Southwark, Streatham, Harlesdon etc. had been taken over. I heard West Africans have taken over Seven Sisters and surroundning neighbourhoods in North London.
Ethnicity, religion, culture etc. are other factors to consider.
Naivety on the part of the Somalis is another factor, in that we have never been exposed to other cultures, religions etc., and tend to come across as belligerent, if intolerant in our dealings with other communities deemed different to us.
Socio-economic standing is another factors to consider, as Somalis move into neighbourhoods traditionally resided by working classes, who view the influx of new arrivals as a threat to their livelihood, perceived as competing for resources, hence scarcity breeding conflict amongst working class communities.
Those tend to breed rivalry, and by extension, animosity. I am sure there are other factors students of Social Studies could speak to.
