United Blood Nation, simply known as U.B.N is a prison gang formed in 1993 within the New York City jail system on Rikers Island's George Mochen Detention Center. G.M.D.C (Sometimes called C-73) was used to segregate problem inmates from the rest of the detention center. They are one of the largest gangs in New York City.
Members of this gang were known for burning three triangular shape circles on their upper right arm to show affiliation to it. Some members would tattoo a bulldog's face on their right hand, the numbers 031 and letters M.O.B to identify themselves from outsiders also.