The South Armagh Brigade of the Provisional Irish Republican Army (IRA) operated during the Troubles in south County Armagh. It was organised into two battalions, one around Jonesborough and another around Crossmaglen. By the 1990s, the South Armagh Brigade was thought to consist of about 40 members, roughly half of them living south of the border. It has allegedly been commanded since the 1970s by Thomas 'Slab' Murphy who is also alleged to be a member of the IRA's Army Council. Compared to other brigades, the South Armagh IRA was seen as an 'independent republic' within the republican movement, retaining a battalion organizational structure and not adopting the cell structure the rest of the IRA was forced to adopt after repeated intelligence failures.

County Armagh is one of the six counties of Northern Ireland and one of the traditional thirty-two counties of Ireland. It is located in the province of Ulster and adjoins the southern shore of Lough Neagh. It borders the Northern Irish counties of Tyrone to the west and Down to the east. The county borders Louth and Monaghan to the south and southwest, which are in the Republic of Ireland. It is named after its county town, Armagh, which derives from the Irish Ard Mhacha, meaning "Macha's height". Macha was a sovereignty goddess in Irish mythology and is said to have been buried on a wooded hill around which the town of Armagh grew. County Armagh is colloquially known as the "Orchard County" because of its many apple orchards.