South Ossetia, officially part of Georgia, is separated from Russia's North Ossetia region by a border running high in the Caucasus Mountains. Much of the region lies more than 1,000 metres above sea level.
A source of tension since the break-up of the Soviet Union, South Ossetia hosted a brief war between Russia and Georgia in 2008. Moscow subsequently recognised South Ossetia as an independent state, and began a process of closer ties that Georgia views as effective annexation.
South Ossetia is inhabited mostly by Ossetians, who speak a language distantly related to Persian. Most ethnic Georgians have been displaced from the region by the two conflicts. They had accounted for about a third of the population prior to the fall of the Soviet Union.
The Ossetians are believed to be descended from tribes which migrated into the area from Asia many hundreds of years ago and settled in what is now North Ossetia.
As the Russian empire expanded into the area in the 18th and 19th centuries, the Ossetians did not join other peoples of the North Caucasus in putting up fierce resistance.
They sided with the Bolshevik forces that occupied Georgia in the early 1920s and, as part of the carve-up which followed, the South Ossetian Autonomous Region was created in Georgia, and North Ossetia was formed in Russia.
In the twilight of the Soviet Union, when nationalist leader Zviad Gamsakhurdia came to power in Georgia, separatist sentiment burgeoned in South Ossetia.
After several outbreaks of violence, the region declared its intention to secede from Georgia in 1990, and in 1992 proclaimed independence.
Sporadic violence involving Georgian irregular forces and Ossetian fighters continued until the summer of 1992 when agreement on the deployment of Georgian, Ossetian and Russian peacekeepers was reached.
Political stalemate followed. Separatist voices became less strident during President Shevardnadze's rule in Georgia, but the issues returned to the foreground when Mikheil Saakashvili replaced him.
Making clear his intention to bring South Ossetia and another breakaway region Abkhazia to heel, Mr Saakashvili offered them autonomy. South Ossetians overwhelmingly rejected the overture in a 2006 referendum.
Tensions came to head in early August 2008, when, after nearly a week of clashes between Georgian troops and separatist forces, Georgia launched a concerted air and ground assault attack on South Ossetia's main city, Tskhinvali.
Within days, Russian forces swept the Georgians out of both South Ossetia and Abkhazia, briefly pursuing them into Georgia proper.
Russia formally recognised both South Ossetia and Abkhazia as independent states after the war, followed by its Latin-American allies Venezuela and Nicaragua and a few Pacific island states.
In April 2009, Russia bolstered its position in South Ossetia by signing a five-year agreement to take formal control of its frontiers with Georgia proper, as well as those of Abkhazia.
In 2015 Russia started to put more pressure on Georgia over South Ossetia. It signed an "alliance and integration agreement" with South Ossetia that abolished border checkpoints.
Georgia viewed this as a closer step towards Russian annexation of the region, and expressed further concern when Russian forces pushed the border fence 1.5 km further into Georgia proper - a short distance from the country's main west-east highway.