* Boston bombing suspects proud of Chechen heritage
* No evidence of motive so far for attacks
* Chechnya's independence bid crushed by Russian forces after two wars
* Chechen fighters have history of attacks on civilians (Adds comment from relative)
April 19 (Reuters) - During the lifetime of the two Boston bombing suspects, their homeland Chechnya has seen two Russian invasions unleash some of Europe's worst bloodshed in generations, and produced fighters who carried out attacks on civilians that shocked the world.
So far there has been no claim of responsibility for the attacks on the Boston Marathon or evidence made public of the motivations of the suspects, brothers Tamerlan and Dzhokhar Tsarnaev.
Both have left a trail on the Internet suggesting they were devout Muslims, proud of their Chechen heritage and supportive of the region's bid for independence from Moscow.
The Boston attacks could bolster President Vladimir Putin, who has long argued that Chechen separatists are nothing but terrorists and sought the West's support against a common foe.
Their uncle, who said the boys brought "disgrace on the entire Chechen ethnicity", said they never lived in Chechnya. Before coming to the United States they were schooled in Dagestan, a neighbouring region that was drawn into Chechnya's violence during the 1990s and has since become the focal point for a simmering Islamist insurgency.
Both provinces are part of the North Caucasus, a mountainous strip of southern Russia populated mainly by Muslim ethnic minorities, with a history of rebellion against Moscow - and brutal Russian repression - dating back centuries.
In Tsarist times, Russian forces fought constant wars against fighters from the Chechen, Dagestani, Ingush and other ethnic groups. Under Stalin, the entire Chechen people was deported to distant central Asia as a potentially hostile nation. Although some returned, some stayed. The Tsarnaevs were raised in remote Kyrgyzstan.
When the Soviet Union broke up in 1991, Chechens sought independence like the people of the 14 other ex-Soviet republics that left Moscow's orbit. But Moscow decided to fight rather than let them leave.
Bombing suspect Dzhokhar Tsarnaev was born in 1993 and given the same name as Dzhokhar Dudayev, the Chechen secessionist leader of the time. Dudayev was killed by a Russian missile in 1996 as his rebel forces were inflicting a humiliating defeat on Russian troops. Pro-independence Chechens still call their capital Grozny "Dzhokhar" in his honour.
Moscow withdrew its forces after a two-year fight but Vladimir Putin, then prime minister, sent them back in 1999, this time crushing the independence movement and putting in place a hand-picked loyalist leader, whose son Ramzan Kadyrov now runs the region with an iron fist.
Kadyrov said Chechnya had nothing to do with the Boston bombings: "The root of evil should be looked for in the United States," he said on the Internet. "(The brothers) grew up and studied in the United States and their attitudes and beliefs were formed there.... Any attempt to make a connection between Chechnya and the Tsarnaevs is in vain."
The two Chechen wars killed tens of thousands of civilians, mainly as a result of mass Russian bombardment of the capital Grozny and villages in the mountains. Hundreds of thousands of people were driven from their homes.
But Chechen fighters lost the sympathy of the West by increasingly adopting Islamist rhetoric and the tactics of ever-deadlier and more brazen attacks on civilians.
In 2002 Chechen fighters seized a Moscow theatre. When Russian troops injected poison gas and stormed it, 129 hostages and 41 Chechen fighters were killed.
The most horrific guerrilla attack took place in Beslan outside Chechnya in 2004. Fighters seized a primary school on the first day of class, rigged it with explosives and held hundreds of children hostage. When Russian troops stormed the building, 331 hostages were killed, half of them children.
Today, the North Causasus region still faces violence from an insurgency led by an Islamist group, the Caucasus Emirate, led by a former Chechen independence guerrilla commander, Doku Umarov. Much of the violence is focused on Dagestan.
The Caucasus Emirate claimed responsibility for a suicide bombing at Moscow's Domodedovo airport in January 2011 that killed 37 people and for suicide bombings on the Moscow subway that killed 40 people in 2010.
A website which tracks the unrest, Caucasus Knot, says insurgency-related violence has killed 61 people this year. Security is an important issue for the 2014 Winter Olympics, which will be held in Sochi, a peaceful part of the North Caucasus hundreds of miles from Chechnya.
On his social media web page, Boston bombing suspect Dzhokhar Tsarnaev jokes about the reputation of people from the North Caucausus for conflict with the authorities: "A car goes by with a Chechen, a Dagestani and an Ingush inside. Question: who is driving?"
The answer: the police.