MS-13 AKA Mara Salvatrucha is made up of Salvadorians who came to Los Angeles because of a civil war in El Salvador.  They got their name by combing La Mara a street gang in El Salvador, with Salvatruchas, a term used to denote members of the Farabundo Marti National Liberation Front.  The 13 was added to pay homage to the California prison gang Mexican Mafia.  They became known as violent very soon because they all had training from El Salvador and were used to fighting.  Most members were deported back to El Salvador where they just got more recruits in the prison system.  When they arrived they had been asked by many to be initiated, which is a beat in for 13 seconds.  The MS-13 has become Central America’s biggest problem. They even went as far as murdering the son of Honduras President Ricardo Maduro. 

The three dots on the hand represent the gang will only lead you to three places. Jail, the hospital, or the grave.