Refer to my earlier question about how multiculturalism is faring in these countries.
You are asking why race riots would occur in Germany or France. You would know why if you were aware of some of the issues and problems France and Germany are having with multiculturalism. How far off the topic do you want me to lead you?
I`m going to bail now, I`ll get banned for talking about ethnic cleansing if I keep this up. If you can`t readily understand the concept of escalation dominance and how distractions are handy for the conduct of stratgic operations then I`m not going to go on about genocide to enlighten you.