Tabur was created (evolved) by the High Evolutionary from a cat. When war broke out in the High Evolutionary’s city of Wundagore, Tabur fled. When Wundagore left Earth, Tabur was left behind as he wasn’t present in the city at the time. The Cat People took Tabur in and tried to make him feel as one of their own, but he still felt like an outcast. When Dr. Leon was creating a ray-gun that would turn Tigra back to human, Tabur stole it and modified the gun to turn targets to more primitive, or “devolved”, versions of themselves. Tabur wanted to rid the Earth of humans so that the Cat People could rule it, but his plan was fated to become no more than a dream. Tigra, along with other Cat People, stopped him and he himself got shot with the ray, reverting back to a normal cat.
Over time, the effects of the ray disappeared and Tabur became his more evolved self again. Tabur then tried to locate the Cat People but failed, as they had all died. After hearing that there was a hidden city of Cat People, Tabur found a way to get to the Land Within. He slew their king and proclaimed himself as ruler. He then rose himself to Balkatar title, so when magicians would call (conjure a summoning), he would be the one to hear the call and be summoned. Then one day Agatha Harkness called to him. Answering the call, he saw Tigra in a more animal form. Tabur changed Tigra back to her humanoid form. He did not do this from the goodness of his heart, but rather because he wanted to mate with Tigra and legitimize his rule. However, Tigra refused his offer and a fight ensued. During the fight Agatha cast a spell, which transferred the dominant cat soul from Tigra to Tabur, reverting him to a cat once more.