Klingon Empire
The Klingon Empire was the official state of the Klingon people. It was founded in the 9th century by Kahless the Unforgettable, who first united the Klingon homeworld of Qo'noS. Since then, the Klingon Empire expanded its sphere of influence by conquering numerous systems and incorporating them. This made the Empire a major power in its region of the galaxy as of the 22nd, 23rd, and 24th centuries.

History 
Main article: Klingon history

The mytho-historical origin of the Klingon Empire revolves around Kahless the Unforgettable, who emerged as a champion of the people in the 9th century AD and became the first Emperor. In the 14th century, the Empire faced one of its biggest threats when a race from the Gamma Quadrant the Klingons called Hur'q invaded Qo'noS. They looted many valuable cultural treasures, including the revered Sword of Kahless, but then left again. In the mid-21st century, the reign of the last Emperor ended and authority passed to the Chancellor of the Klingon High Council. (e.g., ; )

Because of a Human-caused medical crisis and later territorial conflicts, United Earth and subsequently the United Federation of Planets became the Empire's main adversary in the 22nd and 23rd centuries, during which cold as well as hot wars were fought. While the Empire was in disarray as of the first half of the 23rd century, the conflict with the Federation helped to unify the disparate Klingon Houses and stabilized the rule of the Chancellor.  (e.g. ; ; )

After the Praxis disaster of 2293, Chancellor Gorkon pursued peace with the Federation, resulting in the Khitomer Accords and ultimately paving the way for the Treaty of Alliance between both powers. Klingon-Federation cooperation persisted despite interference by the Romulan Star Empire and a Klingon Civil War from 2367 to 2368. (e.g. ; )

In the 2370s, the Dominion, a hegemonic empire from the Gamma Quadrant managed to sow discord among Alpha and Beta Quadrant powers, resulting in yet another brief Federation-Klingon war. Eventually, both powers joined forces and, after a costly war, together defeated the Dominion in 2375. (e.g. )

Territory

Government 

Officially, the Klingon Empire was a feudal monarchy, with power residing in the Emperor, who was traditionally a descendant of Kahless. However, de facto power lay with the Klingon High Council. The position of emperor was abandoned (but not officially abolished) in the mid-21st century, but was revived in 2369 when a group of clerics created a clone of Kahless, who was accepted as the new Emperor, albeit only as a religious figurehead. ()

The Chancellor, the de facto leader of the Empire, was head of the High Council, which consisted of twenty-four members representing various Great Houses (tuqmey, essentially, the nobility). The Chancellor was protected at all times by the Yan-Isleth (Brotherhood of the Sword). ()

Women were not normally permitted to hold seats on the High Council. Despite that, Gowron once offered Ambassador K'Ehleyr a seat on the Council in exchange for her support of his bid to be Chancellor. ()  Also, Azetbur, the daughter of Chancellor Gorkon, was permitted to succeed him as Chancellor in 2293. ()

Various factions almost constantly challenged the leadership of the Empire, and so over time the Klingons developed a strict and rigorous Rite of Succession to determine their leader. According to tradition, one was permitted to challenge the leader on the grounds of cowardice or dishonorable conduct and fight in single combat. Should the challenger slay the incumbent, he assumed the role of the new leader. ()

Because of the Klingon propensity for violence, shrewd Klingon chancellors redirected hostilities outward, where they would otherwise cause a civil war. In the 2150s, the Klingon chancellor instructed Duras to recapture Jonathan Archer after the latter escaped imprisonment on Rura Penthe. In this way, the chancellor focused the blame for certain internal problems on an external cause. ()  Likewise, Gowron focused his soldiers' energies on invading first the Cardassian Union and later the Federation in order to avoid internal conflicts at home. ()

Aside from challenges to the primary leadership of the Empire, there was also frequent feuding between the various Great Houses. Most often, the challenge was made on the floor of the High Council and resolved on the battlefield. However, on occasion, some "dishonorable" House leaders chose to make more insidious attacks by undermining the standing of their enemies. D'Ghor underhandedly attacked the House of Kozak in this way in the early 2370s. ()

Agencies and institutions 
KDA
Klingon Defense Force (KDF)
Klingon Oversight Council
Order of the Bat'leth
Order of Kahless
Klingon High Council
Great Houses
Klingon Imperial information net
Klingon Intelligence
Klingon Medical Division
Warrior caste
Yan-Isleth (Brotherhood of the Sword)

Subject species 

During certain periods of its history, most notably the 2260s, the Klingon Empire employed slavery and operated, as what was described by Starfleet personnel, planets which had been turned into "vast slave labor camps".  A century later, the Klingon Empire had apparently reformed its ways (possibly due to the Treaty of Alliance with the Federation), however many imperial officials still held a very casual attitude about arbitrarily conquering other species.  Subject races who sought independence were considered an annoyance, and in the event independence from the Empire was granted, the option was always available to "conquer them later" if the Empire chose to do so. (, )

Known subject races of the Klingon Empire included:    

 Arin'Sen 
 Kriosians
 Tessic's species (uncertain)
 Xarantine (uncertain)

Economy 
The main currency unit of the Empire was the darsek. (; ; )

The destruction of the Empire's key energy-production facility on the moon of Praxis was a catastrophic event from which recovery was impossible due to the strain of the Empire's enormous military budget on the resources of their economy. This event was critical in establishing peaceful overtures between the Empire and the Federation. ()

Culture 
See: Klingon

Appendices

Background information 
The emblem of the Klingon Empire was designed by  art director Matt Jefferies, and other than the Starfleet insignia, is one of the only emblems to be featured in every Star Trek series. (Star Trek Sticker Book, pg. 16) It first appeared in  on a wall and on the D7 class model.

The unrealized series Star Trek: Phase II would have established a Klingon Empire which would have been based more on Imperial Japan (much like the Romulans were based on the Roman Empire), rather than the Klingon Empire described here, which as commonly regarded as a metaphor for the Soviet Union during the Cold War; see Kitumba.

Many of the notions ultimately ascribed to the Klingon Empire were originally devised by Ronald D. Moore. In a Klingon-defining memo he wrote to Michael Piller before beginning work on , Moore wrote, "Unlike the United Federation of Planets, the Klingon Empire is not an amalgam of several different star systems brought together by common purpose and values. The Klingon Empire sprang from a single, relatively poor planet in a modest star system. The worlds that now make up the Empire were either subjugated in a not-so-distant past or were annexed at the point of a sword. The Empire is efficiently managed and extremely well run. No star system has ever broken away from Klingon rule in over two centuries of steady conquest. This is not to say that the member worlds of the Klingon Empire are straining at the bit to break away from despotic rule. Quite the contrary, the member worlds of the Empire have learned the many advantages and benefits of their association with the Klingons and few would choose to leave, even if given the option." A breakdown of the Empire's political framework was also provided in the memo, explaining that a High Council had ultimate rule over all aspects of Klingon life but that the daily ruling of the planets in the empire was "left to local families and clans" as well as outlining the existence of an almost-completely ceremonial Emperor who had the option of reassuming power if he should decide to do so. ("Sins of the Father" audio commentary, TNG Season 3 Blu-ray)

In the  episode , Wesley Crusher asked Captain Picard if an event happened "before the Klingons joined the Federation." This statement has never been explained in canon and later episodes clearly show a Klingon Empire that didn't join the Federation. However, it is possible he meant that the Klingons joined the Federation as allies. [Per the TNG "bible", the Empire joined the Federation, and in the Season One episode "Heart of Glory", the Federation crest was beside that of the Klingon Empire behind the commander of the Klingon cruiser pursuing the three fugitives.]

External links 
 
 
  – an extensive site with detailed information about Klingon history and culture
  – Klingon Academy 'ampaS tlhIngan – helping to promote Klingon education, culture and family lines

bg:Клингонска империя
cs:Klingonská říše
de:Klingonisches Reich
es:Imperio Klingon
fr:Empire Klingon
ja:クリンゴン帝国
nl:Klingon rijk
pl:Imperium Klingońskie
ru:Клингонская империя
sr:Клингонско царство
sv:Klingonska imperiet
Governments