Generally an aggressive warlike race, as soon as they developed warp drive, the Iccobar used it to attack and enslave several inhabited worlds. It is known that they had trade relations with species such as the Dinasians and the Iconians. As observed by the Iconians from that period, the Iccobar had made no secret that they wanted to possess their gateway technology. Evaluating that the Iccobar were not yet advanced enough to use their gateway technology, the Iconians restricted the Iccobar's access to their gateways, and assigned several Heralds to monitor all Iccobar movement in areas near gateway access points.
Realizing they wouldn't have their so desired gateway technology for good, the Iccobar joined a secret alliance which was being formed to assault the Iconian homeworld and steal their technology. However, during the attack, a few Iconians were able to escape their planet's bombardment, not before deleting all memory banks from their main computers, thus making the use of their gateway technology impossible. (STO mission: "Midnight")
By the 24th century, the discovery of Iconia by the USS Yamato and the USS Enterprise-D revealed relations between ancient Iconian and Iccobar languages. By that time, the Iccobar were extinct, though their planet was still habitable by the 25th century. (TNG episode: "Contagion", STO mission: "Midnight")