Yeah I heard somewhere that the Southsiders (Sureños and the Mexican Mafia :P) are allied to white gangs, at least in prison. But I heard somewhere that Norteños are allied to Crips and Bloods and other African-American gangs.
But I'm not sure where I read or heard it. I guess it was Wikipedia or something, but you can't always trust Wikipedia, since anyone can edit stuff there.