The Kohlan system was an inhabited star system, which was located near to the Argus Array.
In 2367, the USS Enterprise-D was preparing to tow the Cytherian probe to Science Station 402 in the Kohlan system for further study; however, the tow was interrupted when the probe began moving towards the starship. (TNG: "The Nth Degree")
According to Star Trek: Star Charts ("United Federation of Planets I") and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), the Kohlan system was located in the Alpha Quadrant. This was a trinary system with a trio of F-class stars.