Chechnya is a little place in the North Caucasus mountains. Russia is to the North, Turkey is to the Southwest, and Iran is to the Southeast. A lot of the country is mountains.
In the 15th Century, faced with pressure from the Christian Russians, the pagan Chechens converted to Sunni Islam to win the support of the Muslim Ottoman Turkish empire. However, the Chechens weren’t very good Muslims. Paganism remained powerful until early in the 1800s and Chechen Islam absorbed a bunch of pagan practices: mosques were built near streams and Allah was often referred to as Deila, the head god of the pagan Chechens. Furthermore, Muslim religious-based law conflicted with traditional law and people didn’t always think that “sharia” was better. Even today, Chechen Muslims like and continue to use alcohol and tobacco.
After that, Chechnya remained independent—backward as all get-out, but independent—until the end of the 18th Century. At the start of the 19th Century the Russkies started pressing again while the Ottoman Empire crumbled. From 1834 to 1859 an imam (Muslim cleric) named Shamil led a guerrilla war against the Russians. The Russkies won, but the whole region of the North Caucasus saw repeated rebellions for the rest of the century. The whole region tried to set up an independent country after the Russian Revolution (1917-1921), with the grandson of the Imam Shamil among the leaders. That didn’t work: the Reds got control of the place by 1922 and Shamil’s grandson ended up in Germany. The Soviets promised the Caucasus peoples autonomy, but soon reneged on that promise. Discontent bubbled until a new insurgency broke out from 1940 to 1944. The Soviets defeated this rebellion, then deported all 500,000 Chechens to Central Asia. Perhaps 120,000 of them died in the process. After the death of Stalin in 1953, the survivors were allowed to return.
Chastened by this hard experience, the Chechens kept their heads down until the Soviet Union collapsed in 1990. Then the Chechens again declared their independence. Their leader at the time was Dzhokhar Dudayev. The Russians, under Boris Yeltsin, declined to accept Chechen succession. If the Chechens bailed out, then lots of other people would bail out. Two years of incredibly brutal and devastating war followed. Chechens won their independence, but the price was extremely high. The war had wrecked much of the country. Hundreds of thousands of refugees had been driven out of the country. The guerrillas who had fought the war had become radicalized as exponents of “jihad” and had a hard time returning to civilian life, such as it was. The country collapsed into chaos, with kidnappings for ransom becoming the only growth industry. (About 1,300 people were kidnapped for ransom in four years. Mostly, they got out alive, if not all in one piece.)
Worse followed. In 1999, rebel bands attacked into the neighboring Soviet Union; and a series of bombings of Russian apartment buildings killed about 300 civilians. This set off the Second Chechen War. This time the Russkies beat up on the Chechens and re-gained control of the country—sort of. It also set off a civil war between “opportunist”/Sufi Muslim Chechens who supported the Russians and Wahhabist jihadis who fought them. The Kadyrov family, father and son, led the Sufi faction. In 2004 the jihadis killed the father–Akhmad Kadyrov. In 2007, the son—Ramzan Kadyrov—became President of the Chechen Republic. This guerrilla war continued until 2009. Kadyrov takes a dim view of Wahhabism, and of jihadis.
 The Russians blamed these on Chechen terrorists, but a lot of people think the Russian secret service did them as a justification for war. So, when Dzhokhar Tsarnaev’s dad said that some secret service had framed his kids for the Boston Marathon bombing, , that’s where he was coming from.