AT: "xx" The Federation-Klingon border was the division between the United Federation of Planets and the Klingon Empire.
Deep Space K-7 was located near the border in the 23rd century. (TOS: "The Trouble with Tribbles"; DS9: "Trials and Tribble-ations")
The Azure Nebula is a class 11 nebula on the Federation-Klingon border. (VOY: "Flashback")
Following Chancellor Gowron's demand for the Federation to leave the Archanis sector, several representatives from planets on the Federation side of the border urged a preemptive strike on the Klingons. (DS9: "Broken Link")
The Narada emerged in the alternate reality in 2233 next to a star 75,000 kilometers from the border. It attacked and destroyed the USS Kelvin, which was sent to investigate the anomaly. (Star Trek)