|Policemen at the scene of a bombing in Nazran, Ingushetia [AFP]
The North Caucasus, the mountainous regions which lie in the southwest of the Russian Federation, have long been troubled by violence fuelled by poverty, ethnic and religious tensions, corruption and two wars that ravaged Chechnya in the 1990s.
The region, which lies in between the Black and Caspian seas, comprises a number of republics including Chechnya, Dagestan, Ingushetia, North Ossetia, Kabardino-Balkariya, Karachayevo-Cherkessiya and Adygeya.
The area was largely annexed by Russia in the 1800s following the Caucasian war, in which Russian forces fought against a number of tribal groups, many of them Muslim.
In 1944, Joseph Stalin, the Soviet leader, accused the Chechens and their Ingush neighbours of siding with Nazi Germany during World War II - despite thousands of them fighting with the Red Army - and deported half a million of them to Siberia and Central Asia.
Many died as a result of the deportations, and survivors were not allowed back until 1956.
Since the 1990s, Chechnya has been the epicentre of violence in the region, after it made a bid for independence that resulted in two bloody wars.
Tens of thousands of people died in the conflict between separatists and Russian forces, which has now deteriorated into small-scale skirmishes and hit-and-run attacks on police and government officials.
There is also concern over human rights abuses and the safety of journalists and aid workers - with a number of charity workers being kidnapped and killed in recent months.
Memorial and other human rights organisations have suspended their operations in the region as a result of the attacks.
Ramzan Kadyrov, the Chechen leader, has faced accusations of being involved in violence against human rights workers, a charge which he strongly denies.
But security analysts say improved security in Chechnya has pushed violence into neighbouring Ingushetia and Dagestan, where bombings and shootouts have become more frequent.
Ingushetia, which shares cultural, family and religious ties with Chechnya, is a poor, mainly Muslim republic of 400,000 people, that suffered bomb attacks and murders in 2008 as federal forces and rebel fighters fought for control.
Towards the end of 2008, Dmitry Medvedev, Russia's president, appointed Yunus-Bek Yevkurov, a former paratrooper, as head of the region, replacing his unpopular predecessor, Murat Zyazikov.
Yekurov has so far been unable to control the growth of violence, and was seriously injured in a suicide bombing in June 2009.
In recent months, Ingushetia has been the region worst hit by the upturn in violence.
In August, a suspected suicide bomber blew up a police headquarters in Nazran, the capital, killing at least 20 people and injuring scores of others.
Locals say fighting in Ingushetia has been fuelled by a mix of desperate poverty, Islamic radicalism and heavy handed actions by the local security services.
Russian and Ingush officials say publicly that corruption is at shocking levels.
In Dagestan, which lies to the east of Chechnya and Ingushetia, fighting between rebel fighters and Russian forces has also resulted in bloodshed.
Dagestan, regarded as Russia's most ethnically diverse republic, is increasingly gripped by bombings and almost daily clashes among police, rebels and criminal gangs.
In August 2009, seven prostitutes were shot dead by fighters in a bath house, and four policemen were killed by separatists at a nearby checkpoint.
Other regions in the North Caucasus have largely been spared the larger-scale violence seen in other territories, but still suffer from poverty, corruption and ethnic tensions.
North Ossetia, which shares a border with Ingushetia, suffered a spill-over of violence in September 2004, when a band of Chechen-led fighters seized a school in the city of Beslan, killing at least 330 people, half of them children.
In Kabardino-Balkariya, resentment over poverty and police tactics towards unsanctioned worship by young Muslims led to dozens of men attacking government offices in 2005.
About 139 people were killed in the attacks.
In August 2009, Medvedev said that the increasing violence and the recent murders of human rights activists working in the North Caucasus were "political" and aimed at destabilising the region.
The president said unspecified armed groups in the region were receiving support from "foreign sources" that he did not name.