Question: Gang graffiti started back in the 1960s due to the rivalry between the Bloods and gang in Los Angeles, California in what year?

Context articles: Damu Ridas
Barriox13
Gang graffiti
Bloods
Colors (film)
49ers–Rams rivalry
Crips
Grape Street Watts Crips (gang)
Bastards of the Party
Cle Shaheed Sloan

The Damu Ridas were an assortment of Bloods gang members from South Central Los Angeles who recorded the Bloods & Crips collaboration albums "Bangin' on Wax" and "Bangin' on Wax 2... The Saga Continues".
 The Bloods members formed the Damu Ridas, and the Crip members formed Nationwide Rip Ridaz.
Barriox13, B13 in short, is a street gang in South Los Angeles consisting of over 200 members, many of which are inactive.
 It is divided into West Side Barriox13 and East Side Barriox13 gang with all members loyal to the Barriox13 gang.
 It was established in the early 1980s near El Segundo Boulevard and Main St in South Los Angeles, California.
 The Original group of Barriox13 gang members began the gang for self-protection.
 It is a South Side (Sureno) gang loyal to Hispanic prison gangs.
Gang graffiti is the act of spray painting on walls in certain areas to represent your gang.
 Gang graffiti started back in the 1960s due to the rivalry between the Bloods and the Crips and Sureños and Norteños, and continued on until the 1992 Los Angeles riots.
 Today gang graffiti is common in many ghetto neighborhoods.
The Bloods also known as (OBF) Original Blood Family are a primarily, though not exclusively, African American street gang founded in Los Angeles, California.
 The gang is widely known for its rivalry with the Crips.
 They are identified by the red color worn by their members and by particular gang symbols, including distinctive hand signs.
Colors is a 1988 American police procedural action crime film starring Sean Penn and Robert Duvall, and directed by Dennis Hopper.
 The film takes place in the gang ridden neighborhoods of 1980s' South Central Los Angeles, East Los Angeles and the LAPD Rampart Division, and centers on Bob Hodges (Duvall), an experienced Los Angeles Police Department CRASH officer, and his rookie partner, Danny McGavin (Penn), who try to stop the gang violence between the Bloods, the Crips, and Hispanic street gangs.
 "Colors" relaunched Hopper as a director 19 years after "Easy Rider", and inspired discussion over its depiction of gang life and gang violence.
The 49ers–Rams rivalry began in 1950 and became one of the most intense in the National Football League in the 1970s as the two California based teams regularly competed for the NFL's NFC West Division title.
 The intensity of the rivalry is due to the fact that the cities of San Francisco and Los Angeles have long been competitors in the economic, cultural, and political arenas.
 After the Rams' move to St. Louis in 1995, the rivalry had lost its geographical lore though games were still intense regardless of the standings.
 The cultural differences between the West Coast (where the 49ers are based) and Midwest (where the Rams were based) also added to the intensity of the rivalry, until the Rams moved back to Los Angeles in 2016. "
Sports Illustrated" considers their rivalry the 8th best of all time in the National Football League.
The Crips also known as Original Crip Homies (OCH) are a primarily African-American gang.
 They were founded in Los Angeles, California in 1969 mainly by Raymond Washington and Stanley Williams.
 What was once a single alliance between two autonomous gangs is now a loosely connected network of individual "sets", often engaged in open warfare with one another.
 Its members traditionally wear blue clothing, a practice that has waned somewhat due to police crackdowns on gang members.
The Eastside Grape Street Watts Crips (known by the acronyms JDC, GST, WBLC, and GSW) is an African-American Crips subset based in the Watts neighborhood of Los Angeles.
 They're known for being the first original Crip set in Watts.
 The gang is partially located in the Jordan Downs Housing Project, and was named after a north-south street in Watts near 103rd street.
 .
 The gang's rivalry with the Bounty Hunter Bloods has been described as being "the most violent and long lasting feud between two gangs that are in the Watts area."
Bastards of the Party is a 2005 documentary film produced by Alex Demyanenko and directed by former Bloods gang-member Cle Sloan.
 The film explores the creation of two of Los Angeles’s most notorious gangs, the Crips and the Bloods, from the perspective of the Los Angeles community.
 The film also denounces gang violence and presents meaningful solutions from former gang-members to stop this problem.
Cle Shaheed Sloan (born May 22, 1969) is an American activist, actor and documentary director from Los Angeles, California, USA.
 While still a member of Athens Park Bloods, a Los Angeles street gang, Sloan worked to reform gang culture to put an end to gang violence from the inside.