The Karbarrans are an ursine life form that are native to the planet Karbarra which is located in the Local Group. Their race became members of the Sentinels after suffering from the tyranny of the Invid.
Similar to many worlds in the Local Group, the Karbarrans themselves came under siege from the ravenous hordes of the Invid Regent who sought revenge against the Robotech Masters. Thus, it was known that they became bitter enemies with the Invid and it was expected that fighting between the two would have been brutal. As the Invid knew the Karbarrans would not surrender, they decided on a more devious approach and abducted the entire planet's population of children who were held as hostages. All attempts at liberating the children failed and a convocation was held to garner a vision of the future from the Shapings. From it, the Karbarrans discovered that they could not fight the invaders whilst their children were in danger and thus became a subject race of the Invid.
By the time of General T. R. Edwards revolt against the REF, the Karbarrans along with the other Sentinels had already liberated their homeworlds. Whilst the Haydonites provided technical assistance, the Karbarrans offered the REF their industrial might to rebuild their fleet to combat the Invid threat which was appreciated by Admiral Hunter.
In the Robotech II: The Sentinels Roleplaying Game by Palladium Books, this race is called the Carbonarites or the Bearmen of Carbonara.