In the late 2260s, a Federation research outpost on this planet was attacked by unidentified raiders. A hundred civilians were killed in the raid. This was one of several incidents that had taken place since a truce was declared between the Federation and the Klingon Empire. Although there was no proof of Klingon involvement in these incidents, some in the Federation believed them responsible. The Klingons claimed that they had observed the treaty to the letter for three years and that they were not responsible for the raids.
In 2268, while under the influence of the Beta XII-A entity, Pavel Chekov believed he had a brother, Piotr Chekov, who had been killed by the Klingons at the research outpost on Archanis IV. (TOS: "Day of the Dove")
Prior to the beginning of the Federation-Klingon War, Gowron sent a message to the Federation Council, telling them to abandon all starbases and military installations in the sector. During the war, the planet was raided by a Klingon force. As a condition of ending the war, Chancellor Gowron stated that the Federation must allow the Klingon Empire to annex Archanis and other worlds captured by Klingons. Captain Benjamin Sisko told the Klingon leader that he couldn't count on that condition being met. (DS9: "Broken Link", "Apocalypse Rising", "Nor the Battle to the Strong")
Background information Edit
"are-KANE-is" was the pronunciation for this planet's name from the script pronunciation guide for "Broken Link".
This planet, introduced in "Day of the Dove", was originally to have been called Alpha IV. On 13 August 1968, however, Kellam de Forest suggested changing the planet's name to Arcanis IV, as the name Alpha IV did "not conform with proper astronomical nomenclature."  Thereafter, in the revised final draft script of "Day of the Dove", the name of this planet was spelt "Arcanis 4".
The fate of Archanis IV after the brief Federation-Klingon war ended in mid-2373 has not been revealed on screen.
According to the Star Trek: Star Charts (p. 62) and the Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), Archanis IV was located in the Beta Quadrant.