1) The first and oldest real gang is the Chinese Mafia aka Triad. They were the first biggest gang/mafia that started in Asia and was the first in the world. Then followed by the Japanese mafia aka Yakuza, then the Europeans. These Asian Mafias participated in every kind of crime but generally in the blackmarket. Triad is the world's number one drug dealers in Asia and is the biggest underground and most wanted drug-traffickers in the U.S. Asian gangs are the most well-discreet, clever and underground clan. They are the fastest growing gangs in the West Coast according to the 2005 Street Gang census.
2) Just below the ladder is the Italian Mobs. They are one of the most well respected and well known Mafia in the U.S. These guys participate in many types of crimes, usually murder. They act on their plans secretely but are usually busted for leaving clues behind.
3) Street gangs. Bloods, Crips, Mexicans gangs, Asian gangs, etc. These are the clans that also participate in every crime but are usually not very serious. Located in ghetto parts of the city.