The Mempa sector is a region of space within the Klingon Empire, where the Mempa system and Beta Thoridar are located.
This star was the site chosen by the House of Duras in 2367, to gather a large fleet to launch an offensive on Gowron's forces at the beginning of the Klingon Civil War. (TNG: "Redemption")
Although Gowron's troops managed to destroy the Duras supply bases in the sector during the course of the war, the Duras forces, secretly aided by the Romulans, dealt a severe blow to Gowron's forces here, which were forced into a full scale retreat from the Mempa sector to Beta Lankal. (TNG: "Redemption II")