Police say brothers Tamerlan and Dzhokar Tsarnaev are behind the Boston Marathon bombings. The two came from the North Caucasus region, which includes the Russian republic of Chechnya, and moved to Kazakhstan at a young age before coming to the United States several years ago.
Conflict has racked the North Caucasus region for almost two decades, but particularly Chechnya. Find out more about the troubled history of this Russian republic.
Chechen rebels began fighting for independence from Moscow in the 1990s in what became known as the First Chechen War. In 1994, former Russian President Boris Yeltsin ordered Russian troops into Chechnya in an attempt to halt moves toward independence.
The standard of living in the southwestern republic in the Caucasus Mountains is poor, even compared with the rest of Russia.
Unemployment is rampant, infrastructure is poor and infant mortality is high.
The Chechen population of about 1 million is mostly made up of Sunni Muslims, who maintain a distinctly different cultural and linguistic identity from Russian Orthodox Christians.
Tens of thousands have been killed and hundreds of thousands of Chechens displaced in the course of years of fighting with Russian military and security forces. In 2002, Chehen terrorists seized the House of Culture theater in Moscow and took approximately 850 people hostage. Thirty-nine of the attackers are killed, along with at least 129 hostages.
In perhaps the most horrific attack, Chechen separatists took over a school in Beslan in the North Ossetia region in 2004. When the siege ended, more than 330 people had died -- half of them children.
Russian forces essentially regained control of Chechnya in 2000, following a long siege of the capital, Grozny. Since then, violence in Chechnya has ebbed, particularly following the death of Islamist militant Shamil Basayev in July 2006, in neighboring Ingushetia.
Chechen militants have, however, been involved in a series of terror attacks in Russia and the surrounding North Caucasus region in recent years. In 2010, two female suicide bombers hit the Moscow Metro system at the height of rush hour, killing 40 and injuring more than 100.
An International Crisis Group report published in October 2012 warned of the scope for more violence in the North Caucasus region.
It's not clear if the Tsarnaev brothers were radicalized as a result of their apparent Chechen roots. A spokesman for Chechen leader Ramzan Kadyrov said the brothers had not been connected with the Chechen republic for many years, according to Russia's Interfax news agency.
However, Dzhokhar Tsarnaev (L) apparently posted links to Islamic websites and others calling for Chechen independence on what appears to be his page on a Russian language social networking site.