The Old Bailey heard that the two 15-year-old girls were taken by the gang to a house in Brixton, south London, where up to 14 teenage boys - some of whom are still at large - queued up to rape or attempt to rape them.
The horrific assault, in October 1994, has caused lasting torment to the two young victims, who were threatened, taunted and abused by other youngsters after reporting their ordeal to police. So fearful for their safety were they that they were kept in constant pager contact with officers handling their case.
Passing sentence, Judge Gerald Gordon said that the six defendants - all aged 15 or 16 and from the Brixton area - had shown "no remorse" for their actions. He added: "These two girls were subjected to repeated humiliation and degradation by you.
"They were not really treated like human beings. They were treated with callous disregard for their feelings, like sex objects to be used and then cast aside."
The judge said that most, if not all, of the defendants were members of the so-called Younger Younger 28s Posse in Brixton.
In all, the six defendants were convicted of seven rapes and one attempted rape of the first girl and two rapes and two attempted rapes of the second.
Spencer Baptiste, 16, convicted of raping one girl twice and attempting to rape the other, was sentenced to three separate four and a half-year terms of youth detention, to run concurrently.
His half-brother, Darren Evans, 15, was convicted of raping the first girl twice and was sentenced to two four-year terms to run concurrently.
Junior Parkes, 16, was convicted of the attempted rape of the first girl and rape of the second, and was sentenced to two four-year terms to run concurrently.
Dwayne Grant, 15, was convicted of raping the first girl, and was sentenced to a three and a half-year term.
Wayne Shelton, 16, convicted of raping each girl once, was sentenced to two four-year terms to run concurrently.
Ricky Stephenson, 16, was convicted of raping the first girl and attempting to rape the second, and was sentenced to two four-year terms, to run concurrently.
All had pleaded not guilty to the charges.