During the nine-month trial at Swansea Crown Court, the jury was told that the abuse started within families but went on to involve group sex sessions with other paedophiles.
The network sexually assaulted boys and girls in Pembrokeshire barns and on beaches.
Some of the 10 children who gave evidence by videoed interviews and closed circuit television link described how knives and a shotgun were produced to frighten them into silence.
The ringleader of the network, who can only be named by his initials, DD, was given 15 years, the heaviest sentence.
One 10-year-old boy had told how his father and another man abused him in a boat and dropped him into the sea a mile offshore. The adults then circled around him while he was told he would be left in the water next time if he ever spoke about what happened.
Sentencing the group, Mr Justice Kay said the victims were 'a particularly damaged set of children' who will suffer for the rest of their lives from their ordeals.
None of the paedophile ring can be identified in order to protect children involved in the case.
A dozen children are still in council care; their future will be decided by the civil courts.
The judge told the five men: 'There was no evidence of people dressed in long wigs and capes, abusing children. I am satisfied there was no ritual abuse, but that simply carried out for your own perverted gratification.'
DD, 41, was convicted of four counts of conspiracy and two further counts of gross indecency involving a three-year-old girl.
JE, 33, who was also convicted on four conspiracy charges, was jailed for 11 years. His brother, ME, 34, who was convicted on two conspiracy charges, was jailed for seven years.
PJ, 35, who was convicted of two conspiracy charges and was also jailed for seven years. The youngest paedophile, WC, 24, was jailed for five years on four counts of conspiracy. The judge said there was 'sad evidence' that he had graduated from being a victim of abuse, having been introduced to the paedophile ring as a teenager.
A sixth man, SS, 37, who was cleared of taking part in the paedophile conspiracy, was jailed for eight years for committing serious sexual assaults on his two sons.