Beginning around 140 B.C., these pirates became of concern to the Roman Republic, which attempted to ally with the powers of the eastern Mediterranean against them. Rome found, however, that the eastern kingdoms were either too weak to equip the navies required to confront the pirates, or were actively engaged in commerce with them, since the pirates were a major source of slaves feeding the eastern slave markets. The pirates expanded their operations throughout the first decades of the first century B.C., becoming one of the major naval powers of the Mediterranean. This power made them potential allies for many enemies of Rome, and both Mithridates and the rebel Roman general Sertorius, in Hispania, made overtures to and cooperated with the Cilician pirates.
The main trade of the pirates was slavery. Roman merchants bought the most slaves. Roman land owners held large plantations worked by slaves. Sicily was notorious for its slave plantations owned by Romans. Delos became the center of the Mediterranean slave market; other markets included those of Rhodes and Alexandria in Egypt. At its heyday, a 100,000 slaves passed through its markets in a single day. With the plantations came a harsher system of slavery and greater demand. Western Asia was the main supply, and was reduced by piracy and Roman tax farmers.
During the Third Servile War, Spartacus negotiated with the Cilician pirates as potential allies in his struggle against the Roman Republic, but the importance of slaving to the Cilician pirates made any alliance between the pirates and a slave rebellion one fraught with tension and potential for betrayal. Spartacus had dealed with them to bring his rebel army over to Sicily, but the pirates betrayed him, taking the gold he had paid them for their service and leaving him to fight Marcus Crassus. The pirates may have even captured rebels and sold them back into slavery.
- Heracleo - Leader of the cilician pirates
- Orsino - Another leader of the pirates