Baibars Zenge was a Taung Dark Crusader who originated the title Sith Lord. He was the last known Taung to exist because scientists labeled the species extinct due to their lack of presence on Coruscant and Mandalore, the two homeplanets of the Taung. The Crusaders, led by Baibars Zenge, attacked Coruscant. Zenge planned on sacking Coruscant, which would essentially force the Jedi and the Republic to surrender. The sacking of Coruscant failed and the Dark Crusaders were forced to retreat with only the partial destruction of the Jedi Temple to use as a morale boost. Zenge eventually lost the war to the Republic and they were forced into hiding again. Zenge was never seen or heard from again after his defeat to the Jedi. He reportedly came up with the title Sith Lord and its variations called the Dark Lord of the Sith and Sith as a means to separate any connection and "hex" placed on them by the Jedi Order, their parent organization the Dark Crusaders.
Behind the scenes
Baibars Zenge was given the responsibility of changing the Crusaders name from the Dark Crusaders to the Sith once the creator, I'm the Chosen One, realized that there was no plausible explanation for the name change in existence. The creator also wanted to make Zenge's species unique from any other Sith in canon, other fanon and his fanon, so he made Zenge a Taung.