Problem: The Incredible String Band (sometimes abbreviated as ISB) were a psychedelic folk band formed by Clive Palmer, Robin Williamson and Mike Heron in Scotland in 1966. The band built a considerable following, especially in the British counterculture, notably with their albums The 5000 Spirits or the Layers of the Onion, The Hangman's Beautiful Daughter, and Wee Tam and the Big Huge. They became pioneers in psychedelic folk and, through integrating a wide variety of traditional music forms and instruments, in the development of world music. Following Palmer's early departure, Williamson and Heron performed as a duo, later augmented by other musicians.

After that the group lasted another four years, although there was a gradual decline in their status and commercial success after 1970. Joe Boyd, whose skillful handling of the band had contributed much to their international success, stopped managing them and returned to the US. The group left Elektra Records and signed with Island, for whom they recorded five albums. The first was a soundtrack to the "Be Glad..." film, and this was followed by the eclectic Liquid Acrobat as Regards the Air, regarded as their best album for some time.  The band continued to tour and record. Rose Simpson left in 1971 and was replaced by Malcolm Le Maistre, formerly of the Stone Monkey troupe. Mike Heron took time out to record a well-received solo album, Smiling Men with Bad Reputations, which, in contrast to the ISB's self-contained productions, featured a host of session guests, among them Pete Townshend, Ronnie Lane, Keith Moon, John Cale and Richard Thompson. The following year, Licorice left, and was replaced by Gerard Dott, an Edinburgh jazz musician and friend of both Heron and Williamson who had contributed to Smiling Men. Williamson also recorded a solo album, Myrrh, which featured some of his most extraordinary vocal performances.  The group's changing lineup, adding Stan Schnier (aka "Stan Lee") on bass, Jack Ingram on drums, and Graham Forbes on electric guitar reflected moves toward a more conventional amplified rock group. Their final albums for Island were received disappointingly, and the label dropped them in 1974. By then, disagreements between Williamson and Heron about musical policy had become irreconcilable, and they split up in October 1974.

when did the group finally diminish?

Answer with quotes: By then, disagreements between Williamson and Heron about musical policy had become irreconcilable, and they split up in October 1974.

Question:
Public Enemy is an American hip hop group consisting of Chuck D, Flavor Flav, Professor Griff, Khari Wynn, DJ Lord, and the S1W group. Founding member DJ Terminator X left the group in 1999. Formed on Long Island, New York, in 1986, they are known for their politically charged music and criticism of the American media, with an active interest in the frustrations and concerns of the African American community. Their first four albums during the late 1980s and early 1990s were all certified either gold or platinum and were, according to music critic Robert Hilburn in 1998, "the most acclaimed body of work ever by a hip hop act".
Carlton Ridenhour (Chuck D) and William Drayton (Flavor Flav) met at Long Island's Adelphi University in the mid-1980s. Developing his talents as an MC with Flav while delivering furniture for his father's business, Chuck D and Spectrum City, as the group was called, released the record "Check Out the Radio", backed by "Lies", a social commentary--both of which would influence RUSH Productions' Run-D.M.C. and Beastie Boys. Chuck D put out a tape to promote WBAU (the radio station where he was working at the time) and to fend off a local MC who wanted to battle him. He called the tape Public Enemy #1 because he felt like he was being persecuted by people in the local scene. This was the first reference to the notion of a public enemy in any of Chuck D's songs. The single was created by Chuck D with a contribution by Flavor Flav, though this was before the group Public Enemy was officially assembled. Around 1986, Bill Stephney, the former Program Director at WBAU, was approached by Ali Hafezi and offered a position with the label. Stephney accepted, and his first assignment was to help fledgling producer Rick Rubin sign Chuck D, whose song "Public Enemy Number One" Rubin had heard from Andre "Doctor Dre" Brown.  According to the book The History of Rap Music by Cookie Lommel, "Stephney thought it was time to mesh the hard-hitting style of Run DMC with politics that addressed black youth. Chuck recruited Spectrum City, which included Hank Shocklee, his brother Keith Shocklee, and Eric "Vietnam" Sadler, collectively known as the Bomb Squad, to be his production team and added another Spectrum City partner, Professor Griff, to become the group's Minister of Information. With the addition of Flavor Flav and another local mobile DJ named Terminator X, the group Public Enemy was born." According to Chuck, The S1W, which stands for Security of the First World, "represents that the black man can be just as intelligent as he is strong. It stands for the fact that we're not third-world people, we're first-world people; we're the original people." Hank Shocklee came up with the name Public Enemy based on "underdog love and their developing politics" and the idea from Def Jam staffer Bill Stephney following the Howard Beach racial incident, Bernhard Goetz, and the death of Michael Stewart: "The Black man is definitely the public enemy."  Public Enemy started out as opening act for the Beastie Boys during the latter's Licensed to Ill popularity, and in 1987 released their debut album Yo! Bum Rush the Show.
Answer this question using a quote from the text above:

When did they first perform as Public Enemy?

Answer:
With the addition of Flavor Flav and another local mobile DJ named Terminator X, the group Public Enemy was born.