The Ballas have been around since the 1970's Specific information regarding where or how they formed is unknown. However, it is likely that the Ballas evolved either from Glen Park or Jefferson since Idlewood and possibly Willowfield were controlled by the Grove Street Families prior to 1992 and since East Los Santos was split between the Grove Street Families and the Vagos prior to 1992.
The Ballas have a history of a traditional, intense, and bloody rivalry with the Grove Street Families. Specifically when the gang war started is unknown, but the rivalry between the two gangs was in full swing as early as 1987.
The Ballas were responsible for the death of Beverly Johnson - the mother of Carl Johnson and Grove Street leader Sweet in a drive-by shooting that was targeting the Johnson House in Grove Street. The actual objective was to hit Sweet, but he was elsewhere. In addition to this, it is likely that the Ballas were also responsible for the death of many Grove Street OG's - including Little Devil, Big Devil, and Tony (GSF) though the game doesn't specifically mention that it was the Ballas.
It is also highly likely that the Ballas were responsible for the death of Brian Johnson - the younger brother of CJ and Sweet, though the game doesn't mention the actual cause of Brian's death.
