Complex sentence: Those who were victimized by Crips joined the Pirus and Brims and ran with the Blood identity, that's how the Blood gang was formed; note the Bloods started in jail in LA County in 1974, Pirus and Brims both formed on the streets in 1972.
Split into simpler sentences: Those who were victimized by the Crips joined the Pirus and Brims and ran with the Blood identity, which is how the Blood gang was formed. The Bloods started in jail in LA County in 1974, and the Pirus and Brims both formed on the streets in 1972.