
The Klingon Empire is led by the humanoid Klingon species, from the planet Qo'noS in the Beta Quadrant, and along with the United Federation of Planets and the Romulan Star Empire, is one of the Great Powers of the known galaxy in the era of Star Trek: Discovery. It has gone through several periods of political change in the time the Federation has known it, evolving from an intractable antagonist in Burnham's and Kirk's era, to principle ally in the era of Picard, Sisko and Janeway. Led by a High Council and a Chancellor, it is unknown how extensive the empire is, but may be as vast as the Federation, and probably incorporates many subject species.
In the past we have been able to see distinct phases of Klingon culture separated roughly by three eras:
- Archer's era - the 22nd century
- Kirk's era - the 23rd century
- Picard's era - the 24th century
How does Burnham's era (23rd century) fit in? What can we piece together about Klingon history now, in light of the premiere episodes? Let's take a look at what we know.

Speculation (based on conflicting dates in episodes)
- 9th century - Kahless defeats Molor and unites the Klingon people into the Klingon Empire
- 14th century - The Hur'q, humanoids from Gamma Quadrant, sack/loot Qo'noS
- 16th century - The traditional monarchy descended from the family of Kahless is put to death
- 16th century - A new third dynasty assumes power and claims descent from the previous one
- 21st century - Klingons gain warp drive by at least this point

Reliable recorded history
- 20?? - First contact with planet Vulcan results in decades of hostility
- 20?? - The monarchy is abolished, with the position of Emperor defunct
- 20?? - The Klingon Empire is now led by the position of Chancellor
- 20?? - An invasion of Breen is launched and never heard from again

Archer's era - (Klingon Empire is feudal aristocracy/oligarchy)
- 2151 - The Suliban seek to destabilize the Klingon Empire through terrorism
- 2151 - First contact with planet Earth results in decades of hostility
- 2152 - A human starship captain is put on trial, and escapes the Rura Penthe gulag
- 2154 - A failed eugenics program leaves Klingons with deformities via a retrovirus
- [Approx 100 year period of isolation begins]

Burnham's era - (Klingon Empire is politically unstable/unknown government)
- [Federation-Klingon Cold War begins]
- 22?? - Attack on Vulcan colony at Doctari Alpha
- 2245 - Battle of Donatu V
- 2256 - Battle of the Binary Stars
- [Approx 100 year period of isolation ends]
- 2256 - 1st Klingon-Federation War: Klingon offensive against Federation

Kirk's era - Klingon Empire is military dictatorship (as per TOS "Errand of Mercy")
- 2267 - Invasion and occupation of Organia
- 2267 - 2nd Klingon-Federation War: Organian Peace Treaty signed
- 2268 - Klingons sign treaty with The Romulan Star Empire and exchange tech
- 2271 - Klingon-Romulan relations break down by the Battle of Klach D'kel Bracht
- 2285 - Attempts to gain Project Genesis superweapon through unsanctioned attack
- 2293 - Praxis, a moon of the Klingon homeworld, is destroyed in a mining accident
- 2293 - Peace signed at Khitomer as the Klingon homeworld faces environmental crisis
- [Federation-Klingon Cold War ends]

Picard's era - Klingon Empire is aristocracy or oligarchy or limited democracy
- 2344 - Romulan attack on Narendra III, Federation sends support
- 2346 - Romulan attack on Khitomer
- 2366 - Klingons send support to Federation against the Romulans
- 2367 - Klingons send support to Federation against the Borg
- 2368 - Klingon Civil War: Romulans seek to place pro-Romulan faction in power
- 2372 - 3rd Klingon-Federation War: Khitomer accords break down, war is declared
- 2373 - Dominion War: Peace signed, and joint war against The Dominion declared

So what can we determine from what we have seen? It seems that multiple races of Klingons have existed in the Klingon Empire, possibly owing to cross-marriage with other humanoid species within the empire - different planets or colonies within the empire may have developed different ethnic groups of Klingons over the centuries, with both cosmopolitan and relict populations. It seems that Klingons have entered a period of isolation for a while, just like the Romulans, except less scrupulously maintained - there seems to have been enough hostile contact for a Cold War to develop between the United Federation of Planets and the Klingon Empire. For comparison, lets contrast Romulan and Klingon history:
The Romulan Star Empire:
- Earth Romulan War (ends with the signing of the peace after Battle of Cheron) (2156-2160)
- [Long Isolation] (2160-2266 - 106 years)
- Balance of Terror attack tests the Federation and deploys functional cloaking device (2266-2268)
- Attempt to disrupt the Federation-Klingon peace by supporting Chang and Cartwright (2293)
- [Short Isolation] (2311-2364 - 53 years)
- Reemergence in TNG in response to Borg attacks on Romulan and Federation bases (2364)
- Attempt to disrupt the Federation-Klingon peace through regime change on Qo'noS (2367)
- Attempt at re-unification of Vulcan and Romulus via a coup led by Romulan troops (2368)
- Tal Shiar and Obsidian Order launch a first strike on the Founders of the Dominion (2371)
- The Dominion War (ends with the signing of the peace after Battle of Cardassia) (2374-2375)
- First contact with Vulcan (results in animosity between Vulcan and Klingon starships) (2016?)
- First contact with Earth (results in fear of Earth's history of eugenics and militancy) (2151)
- Failed eugenics program unleashes retroviral DNA vector into the Klingon poulation (2154)
- [Isolation] (21??-2256 - "a hundred years")
- Klingon Empire emerges from isolation in an encounter with the USS Shenzhou (2256)
- Start of an open Klingon-Federation war, and signing of Organian Peace Treaty (2267)
- End of Cold War, explosion of Praxis, and signing of the Khitomer Accords (2293)
- Attempt by the Romulans to disrupt the Federation-Klingon Alliance via Duras (2367)
- Breakdown in relations due to Dominion disruption leads to brief open war (2372)
- The Dominion War (ends with the signing of the peace after Battle of Cardassia) (2373)
The first episodes of Star Trek: Discovery center around the emergence of a Klingon extremist who styles himself as a successor of Kahless, and who, suffering from an inferiority complex, wishes to cynically unite his culture by projecting the United Federation of Planets as an enemy. The Klingons have maintained a Cold War with the newly powerful democratic Federation for a century, but owing to internal struggles, their attentions have largely fallen elsewhere. By calling upon xenophobia toward the Federation, and then provoking a battle against them, T'Kuvma wishes to present himself as a martyr for Klingons to rally around.
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