(covers information from several alternate timelines)
The Treaty of Organia, also known as the Organian Peace Treaty, was an agreement enforced by the Organians, a race of powerful incorporeal beings of Organia, upon the United Federation of Planets and the Klingon Empire, ending the Federation-Klingon War in 2267. (TOS: "Errand of Mercy")
According to the terms of the treaty, each side could lay claim to a disputed planet inside the Neutral Zone between the two powers, and was given the opportunity to demonstrate its ability to develop that planet most efficiently. Also, each side was granted the right to demand use of the other's shore leave facilities along the border. (TOS: "The Trouble with Tribbles")
The Treaty of Organia was eventually superseded by the Khitomer Accords of 2293, which bore out the Organians having predicted that the Klingons and the Federation would one day become friends. (Star Trek VI: The Undiscovered Country)
In the alternate reality, this treaty was in existence by February 2259. On the eve of the founding of Sherman's Planet, there was a dispute about this treaty. (Star Trek Into Darkness, production art)
The actions of "A Private Little War" were said to break "the treaty" and therefore might trigger war between the Federation and the Klingons, but it was not explicitly said that this was the same treaty as the Organian one. If it was the same treaty, it would mean it did not allow indigenous native populations to be disturbed, except under the auspices of pure scientific exploration and research, and the Klingons would have violated it by giving flintlock rifles to the primitive inhabitants of the planet Neural.
In Star Trek III: The Search for Spock, Kirk later informed Kruge that "By violation of treaty between the Federation and the Klingon Empire, your presence here [at Genesis] is an act of war." As before, it was not explicitly said that this was the same treaty as the Organian one, as no other treaties were know to be instated during this period of time.
According to the novel The Klingon Gambit, by Robert E. Vardeman, the Treaty of Organia covered a seven-hundred-and-fifty parsec zone. The novel How Much for Just the Planet? sums up the Organian Treaty as "Don't get grabby, or you'll get your fingers burned."
Federation: The First 150 Years states that the Treaty of Organia was recorded on an advanced disk that, when touched, would detail the following provisions of the treaty:
- Worlds in dispute – All worlds currently in the previously described Disputed Area between the two parties are now considered neutral.
- Further, any worlds that may be discovered from this point forward that lie in the one parsec overlap between the nearest Federation and Klingon outposts shall be considered neutral.
- No party may seek to use a new world for military purposes.
- If both parties seek to make use of the world to provide sustenance to their civilization, they must make a case to the Organian Council of Elders that their plans for it are efficient and non-militaristic.
- Any attempt to violate this section of the agreement will result in the permanent immobilization of the offending party's fleets and space habitats.
- All beings belonging to the offending party's species will be immediately and permanently returned to their homeworld.
According to The First 150 Years, the circumstances of the treaty being forced upon them by the Organians was a source of great embarrassment for both the Federation and the Klingon Empire. The Federation, in particular, was highly dissatisfied with the fact that the Klingons were granted access to Federation facilities, and sought to replace it with something that would keep the Klingons confined to their own borders. The induction of Coridanite into the Federation provided the opportunity to do just that. In The First 150 Years, Coridan's admission into the Federation supplies them with a large supply of dilithium, allowing them to give up claims to a great number of dilithium-rich planets in the Disputed Area (referenced in "Errand of Mercy") to the Klingons in exchange for new treaty that would establish a neutral zone between the two governments and keep the Klingons out of Federation space.