I don't think the Mexican gangs 'took over' the black neighborhoods. In a neighborhood where the vast majority is African-American, a Mexican minority won't have a chance. The Aryan Brotherhood and La Eme have an alliance because they have mutual enemies. They also do some business together like working in the drug trade, etc... Black gang aren't really big in the Texan criminal world. It's mostly Chicanos and Mexican immigrants and a lot of whites doing the dirty stuff over there. Arizona is also mostly controlled by outlaw motorcycle gangs and Hispanic gangs.
Most of the southwest is controlled by hispanic gangs but whites are also there with the Hispanics. Mexicans criminals in general don't trust blacks.
Actually , mexicans (or chicanos) in northern cali are allied with black gangs and do business with each other. Its the southern cali mexicans (who are largely in control by the mexican mafia) who have the gripe with blacks and ally with white supremacist (which is bizarre in itself).
The most bizarre thing is , if you go on youtube and type in "lowrider oldies" or what have you , you will find videos made by these southern cali chicano gang members. They attach their gang pictures to old soul/r&b songs from blacks , and yet , they hate blacks lol
The above video is from a Doo Wop group called the Paragons from back in the day. Florencia 13 ( a sureno gang notoriously known for their violence towards blacks in general) have actually adopted it as their theme song rofl
