Caucasus: Chechnya
Longterm conflict, subsided but not resolved. Muslim Chechens vs Secular/Orthodox Russia, with internal civil rivalries too. Deaths 100,000+.
The first war was in 1994-96 (50,000-100,000 dead), the second in 1999-2006 (25,000-120,000 dead). Many atrocities, much social and environmental damage.
Muslim Chechnya was originally annexed by Russia in 1870. Mass deportation of Chechens to Kazakhstan and Siberia 1944-56 by Stalin (alienating Chechens against Russia). Domination of Chechnya by Chechen crime clans in 1980s (linked with the Afghan war against USSR), leading to civil strife, then to unilateral declaration of independence in 1991.
Russian intervention 1994-96, unsuccessfully. The conflict eventually subsided and independence was nearly achieved, but Chechen radicals brought new internal chaos, leading to a new Russian intervention in 1999.
There have been differences of aim between Chechen nationalists fighting on local issues and international Muslim jihadis trained in Afghanistan and Pakistan, fighting Russia for geopolitical ends. The conflict subsided by 2006, mainly from exhaustion.
Chechnya is now ruled by a pro-Russian Chechen government. Occasional localised chaos and violence continues. Risk of spread of the conflict to neighbouring Ingushetia. 40% of the 1.4m Chechens have now left Chechnya.
LINKS:
BBC: the Chechen Conflict
BBC: Chechen Timeline
Wikipedia: Chechnya
Flashpoints: Chechnya
The Guardian: Chechnya feature