A region of Klingon space where Gowron's fleet met the forces of the House of Duras in a major engagement of the civil war of 2367 to 2368.
The Mempa sector is a region of the Klingon Empire named in the two-part Next Generation story Redemption.
After Gowron is installed as chancellor, Lursa, B'Etor and the young Toral lead a rebellion against him. Fighting spreads across the Empire, and the Mempa sector becomes the scene of one of its largest battles, which goes badly for Gowron's side.
Worf and his brother Kurn both serve in the campaign. The run of defeats, made possible by supplies the Duras family secretly receive from the Romulans, convinces Picard to propose a Starfleet blockade of the Romulan border. Once the convoys are stopped, the Duras forces collapse.