It's not only a group, it's more a philosophy
As detailed in the film Tupac: Resurrection the concept of "Thug Life" was viewed by Shakur as a philosophy for life. Shakur developed the word into an acronym standing for "The Hate U Gave Little Infants Fucks Everybody." He declared that the dictionary definition of a "thug" as being a rogue or criminal was not how he used the term, but rather he meant someone who came from oppressive or squalid background and little opportunity but still made a life for themselves and were proud.
"I didn't create Thug Life, I diagnosed it."
Thug Life became a calling card for how Shakur viewed his influence on society. He had people from all walks of life - criminals in jail, white kids in the suburbs, poor black kids in the ghetto - wanting to know how they could be a part of his movement. Shakur admitted this sudden power he had over people frightened him. But he used the idea of Thug Life to transform the desires of these people into something he viewed as positive, a way to reach out to the poor, the disenfranchised, and the oppressed. Gang members instituted what was called the Code of Thug Life, and gangs from New York to Chicago to Los Angeles claimed to abide by it. Examples of the rules in this Code of Ethics were that civilians were not to be targets in gang warfare, and that children in schools should not be indoctrinated by gang propaganda.
Shakur's philosophy of Thug Life was met with harsh criticism from most of the leaders in government and politics, including many notables in the black community.