Two main planets in the Tzenkethi Coalition were Tzenketh and Ab-Tzenketh, with the latter being a natural satellite orbiting the former. Ab-Tzenketh was the ruling capital of the Tzenkethi Coalition.
During the late 2350s and early 2360s, the Tzenkethi Coalition and United Federation of Planets were involved in the Federation-Tzenkethi War. (Star Trek: Deep Space Nine) After the war, the then-Autarch and his tzelnira were overthrown, and all but one tzelnira were hunted down and assassinated by the new Autarch and his followers. (Star Trek: The Prospect Chronicles: "The Tzenkethi Incident")
In 2365, an overthrown tzelnira named Zir'kemth attempted to regain power by blaming Starfleet for terrorist attacks on several Tzenkethi member worlds. (Star Trek: The Prospect Chronicles: "Mass Extinction")