The Turkana system was an inhabited planetary system. An Earth colony was established on Turkana IV. This colony disintegrated into internecine warfare and eventually severed relations with the Federation.
In 2352, the crew of a Starfleet starship rescues Tasha Yar from Turkana IV. (TNG: "Encounter at Farpoint", "The Naked Now", "Legacy")
In 2361, the starship USS Potemkin visited the system. The colonists issued a warning to the starship captain not to beam any of his crew down. (TNG: "Legacy")
In 2367, the USS Enterprise-D entered this system in response to a distress call from the freighter Arcos. (TNG: "Legacy")
In 2371, the location of Turkana IV was labeled in the star chart Data and Picard were studying in stellar cartography aboard the USS Enterprise-D. (Star Trek Generations, display graphic)
The system may have been named after the Turkana, a culture of Kenya, Africa.