I suppose there will be many white or non black gangs through out the gang such as perhaps the mafia, biker gangs, red necks, Yakuza, etc. The only non black/hispanic gang that has been confirmed is the Triads, which will most likely be located in Chinatown, San Fierro.

"You can shear a sheep many times, but you can skin him only once."
-Amarillo Slim