Russian troops drove militants into Chechnya in 1999
Together with neighbouring republics of the North Caucasus region - Chechnya, Ingushetia, and Northern Ossetia - it forms part of Russia's most unstable region.
Dagestan itself is home to some 32 small nationalities, held in a rather precarious equilibrium by a constitution that prevents any one of them acquiring too much power.
Most of the two-million-strong population is nominally Sunni Muslim, but in some villages, especially in the villages of the central mountains and foothills, ultra-orthodox Wahabis have moved in and taken over from the established moderate church leaders.
Bombings
In two villages they have even gained responsibility from the government for maintaining public order - within the limits prescribed by the Russian constitution.
The 1994-1996 war in Chechnya left a powerful mark on Dagestan.
(Click here to see a map of the region)
Among the Dagestani fighters who took part in the war, on the Chechen side, were young religious radicals who returned home with the goal of establishing an independent Islamic state.
In 1999, they joined two major Chechen warlords in an attempt to establish an independent Islamic republic, but were quickly crushed by the Russian army.
These clashes - and a string of apartment-block bombings that ensued, in Dagestan and other parts of Russia - led the Russian Government (under the country's future president Vladimir Putin) to launch a second major military offensive against Chechnya, later that year.
Though the worst of the fighting in Chechnya is now over, Russian forces stationed there are subject to constant harassment from rebel fighters, including ambushes and bombings.
Organised crime
Dagestan is also sufficiently lawless for Russian soldiers and police to be vulnerable.
Violent organised crime is also a major problem in the republic, with rival clans vying for influence in politics and business, such as the Caspian fishing and caviar trade.
Bomb attacks, kidnappings and political assassinations are not uncommon.
While the largest ethnic group - the Avars - have made several attempts to establish a presidential chief executive to replace the existing collective state council, rival ethnic groups have always had enough sense to pull back from large-scale bloodshed.
The republic is sometimes known as the Mountain of Languages, or Mountain of Nationalities - with some national groups occupying no more than one or two villages - and is often compared to the Tower of Babel.
All its inhabitants know that in such a fragmented society the consequences of chaos - in the worst case, an all-against-all conflict - do not bear contemplating.
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Related to this story:
The first bloody battle
(16 Mar 00 | Europe)