I'm not trying to make any sweeping generalisations but when i lived in scotland there was a very low number of "minority groups" and since living in coventry its been an eye opener for me to the different views from various groups on how things should be done. Granted it can be down to a cultural difference in ways of living or doing business and hence im not blaming individuals but damn it can make things difficult/depressing at times when your trying to get stuff done.
It seems some people believe that because it's how their culture deals with something that makes it right for them to do it a certain way, where as, i see it that they should conform to where they live. When I have lived in other countries I've adjusted the way i do things to match local tradition and culture, it only seems fair.
Sadly when large enough groups are formed (be that due to pressure to push similar groups into one area by councils or just human nature to be around those similar to you) it seems a micro nation is formed with its own territory, lifestyle and rules. I have to admit its really quite intimidating one minute driving or walking along a "normal" street then all of a sudden its a completely alien world as you turn a corner. At first I accepted this as the norm and got on with it but more and more i seem to get frustrated by the differences.
As far as extremists go, every culture has them, from football hooligans slashing each other with stanley blades and rioting to terrorist attacks causing mass panic. Some we are accustomed too, some are new, they will always be around in some form and there is naff all we can do to prevent the crazy people venting via one excuse or another.