Military district
The headquarters is in Da Nang.
7th Military Region: It is directly under the Ministry of Defense of Vietnam; tasked to organize, build, manage and command armed forces defending southeastern Vietnam. The headquarters is in Ho Chi Minh City.
9th Military Region: It is directly under the Ministry of Defense of Vietnam; tasked to organize, build, manage and command armed forces defending the Mekong Delta. The headquarters is in Cần Thơ
The Army of the Republic of Vietnam originally had four corps, for example I Corps (South Vietnam). Later they were redesignated Military Regions 1–4.

See also: Unified Combatant Command
United States historical military districts
Fortified district

References: 
Beevor, Antony (1991). Inside the British Army. Reading: Corgi Books. ISBN 0552138185.
Feskov, V.I.; K.A. Kalashnikov; V.I. Golikov (2004). The Soviet Army in the Years of the 'Cold War' (1945–1991). Tomsk: Tomsk University Press. ISBN 5-7511-1819-7.
Isby, David C.; Kamps, Charles T. (1985). Armies of NATO's Central Front. London: Jane's Information Group. ISBN 0-7106-0341-X.
Werenfels, Isabelle. Managing Instability in Algeria: Elites and Political Change since 1995.