The Dnyarri were an ancient, extremely evil race who could control the minds of others. They resembled large, brown toads with a grossly pulsating skull and sinister looking face. Their discovery by a young Ur-Quan scout allowed the psychic Dnyarri to quickly dominate the Sentient Milieu. The Ur-Quan were enslaved for thousands of years under the Dnyarri's yoke, and were eventually split in to the Kzer-Za and the Kohr-Ah.
The Dnyarri favored the Ur-Quan over the other species of the Milieu, due to their weak resistance to mind control. They used the Ur-Quan to wipe out many member races of the Milieu over time. During this period, the Dnyarri re-engineered the Ur-Quan DNA into two types, the green (Kzer-Za) who were the political leaders and scientists, and the black (Kohr-Ah) who were the builders, warriors, and general "do"ers.
The Green Ur-Quan researcher Kzer-za found out that the Dnyarri had to disconnect from a slave´s mind if the slave experienced extreme pain. Kzer-za broadcast this discovery to the rest of the Ur-Quan, who started inflicting pain and agony upon themselves to relinquish their minds from the Dnyarri control. The freed Ur-Quan slaughtered the Dnyarri en masse.
Death wasn't a good enough punishment for the Dnyarri in the eyes of the Ur-Quan. As they had been engineered, so too did the Ur-Quan re-engineer the Dnyarri into sub-sentience, making eternal slaves of them, using them to communicate for them whenever they communicated with a species they felt was less advanced than they were (which was often). These Talking Pets are used aboard all Dreadnought and Marauder vessels.