Final answer:
The arch-rivals of the Bloods are the Crips, with a rivalry rooted deep in Los Angeles's history, often highlighted by territorial graffiti.
Step-by-step explanation:
The Bloods' arch-rivals are the Crips. These two gangs have a notorious and long-standing rivalry in Los Angeles and other cities. The rivalry between the Bloods and Crips dates back to approximately the 1960s and 1970s, and the conflict has been marked by periods of extreme violence and crime.
Gangs often use graffiti as a way to mark their territory and challenge their rivals, as noted in the reference to East Los Angeles territorial disputes marked by graffiti. This rivalry has become emblematic of the broader issues of gang violence and street crime in American urban centers.