Aion
The Aion are a six limbed grazing herbivores with a superficial resemblence to K'kree. They bear live young, usually only one at a time. Like K'kree, the walk upon four legs, using their fore limbs, equipped with three dextrous fingers, as manipulative limbs. The have a covering of fine brown fur.
The Aion are unusual in that they achieve sentience between 500,000 and one million years ago, the exact dates are uncertain. They had built a sophisticated and technological society, including achiveing space travel. They explored the systems in the space around their homeworld.
Because they had found no other sentient species, they decided to return to their animal existance until there were others to be with. They used genetic engineering to provide a significant racial memory and provide a trigger mechanism to return them to sentience.
They remained in the state until contacted by the IISS. The genetic triggers caused resurgance of the intelligence in the Aion over two to three generations, with the encoded cultural information coming to the fore.
The Aion are still primitive, but only because they are still in the process of recovering their sentientence and need to build rebuild their technological infrastructure. But they are glad to now have the company.