Creature:Cat

After the Humans left Earth, left behind feral cats eventually became sentient and developed space travel. Once space travel was invented among the cats, they all moved halfway across the Milky Way to the planet Yoshii.

Evolution
After humans left Earth, cats slowly evolved into sapient creatures. They started to walk on two legs and use their front paws to grasp things. Eventually, they developed bigger brains and higher intelligence and began to form tribes, then nations, then an empire.