The Kriosian system, also known as the Krios system, was an inhabited planetary system in the Beta Quadrant. The system contained the inhabited planet Krios Prime.
In 2256, this system's location was labeled on the star chart "Alpha/Beta Quadrant Overview" in the ready room aboard the USS Discovery. It was located in the territory of the Klingon Empire. (DIS: "Magic to Make the Sanest Man Go Mad", "The War Without, The War Within")
A year later, its location was labeled on the star chart showing the trajectory of Lieutenant Spock's shuttle. (DIS: "An Obol for Charon")
By the 2360s, this system was on the border of Federation space. (TNG: "The Mind's Eye")
The USS Enterprise-D visited the system twice, in late 2367 and in 2368. (TNG: "The Mind's Eye", "The Perfect Mate")
In 2399, the system's location in neutral space was labeled on a Federation star chart that was in Fleet Admiral Kirsten Clancy's office at Starfleet Headquarters. (PIC: "Maps and Legends")