Kitumba
"Kitumba" was a projected two-part episode for the unrealized Star Trek series Star Trek: Phase II. The episode was written by John Meredyth Lucas. Jon Povill enthusiastically described the story as "a wonderful adventure inside the heart of the Klingon Empire." (Star Trek Phase II: The Lost Series, p. 3)

Plot 
The  under Captain James T. Kirk is sent on a secret mission. Kirk is to take a Klingon warrior named Ksia to the Klingon homeworld. Ksia was once the tutor of the reclusive ceremonial ruler of the Klingon Empire, the Kitumba. But Ksia defected to the Federation in order to prevent the imminent all-out attack of the Klingons on the Federation. This attack was conceived by Malkthon, who is the Klingon Warlord, the actual political ruler of the Empire. Ksia plans to convince the adolescent Kitumba to speak out against the imminent attack as Ksia is convinced that the resulting war would destroy both the Federation and the Klingon Empire. (Star Trek: Phase II - The Making of the Lost Series)

The alternate Klingon Empire 
The episode "Kitumba" would have established a Klingon Empire which differs from the canon Klingon Empire in some notable respects:

The home star of the Klingon Empire is orbited by two M-class planets, the innermost planet being the Sacred Planet of the Kitumba, while the second planet, the actual homeworld, is called Ultar. The canon homeworld of the Klingon Empire is called Qo'noS.
Ultar and the Sacred Planet feature no defense systems since the Klingons believe in their invincibility.
"Klingon" is not the name of the species. Only members of the warrior caste are called Klingons. There are two further castes, the technos, which is the caste of scientists and technicians, and the subjects.
The Klingon Empire is not ruled by the Klingon High Council and its chancellor. There is a ceremonial head of state, the Kitumba, who is revered as a near-god and resides in seclusion on the Sacred Planet. All political and military authority lies with the Warlord, who resides on Ultar.
The Klingon government in "Kitumba" would have been based on Imperial Japan, much like how the Romulan Empire was based on the Roman Empire. The Warlord would have been analogous to the , who held the real political power in Japan for centuries, while the Kitumba, like the , would have been relegated to a ceremonial role. (Star Trek: Phase II - The Making of the Lost Series)

Plot elements of "Kitumba" used in TNG episodes 
The defector who commits treason in order to save his people from a catastrophic war appears as the Romulan Admiral Alidar Jarok in .
The rank of a ceremonial emperor of the Klingon Empire as a spiritual figure is re-introduced in .  
The TNG episodes , , and  featured the captain of the Enterprise, now Jean-Luc Picard instead of Kirk, dealing with the leadership of the Klingon Empire and making crucial decisions concerning the future of the Federation and the Klingon Empire.   
The TNG episodes  and  featured the captain of the Enterprise, again Picard, conducting a covert mission into the homeworld of an enemy empire, now the Romulan Star Empire.

Fan film 
This story was adapted into a fan film, released on . Star Trek Phase II: Episode 1X08 "Kitumba"
Undeveloped episodes