Why are Armenia and Azerbaijan fighting?

Over the past couple of years, Armenia and Azerbaijan have been fighting over territory control. This territory is called Nagorno-Karabakh, an Armenian enclave that is internationally recognised as being part of Azerbaijan. Armenia has a Christian majority while Azerbaijan has a Muslim majority and while the two Caucasus based nations have been squabbling for centuries, Nagorno- Karabakh only became a problem when the Soviet Union conquered the Caucasus which became independent in the aftermath of the Russian Revolution in 1917. Soviet leader Joseph Stalin is to blame for the current region drama because he stole Nagorno-Karabakh (known as Artsakh to the Armenians) from Armenia in 1921 and put it in Azerbaijan the same year. Thus when the Soviet Union collapsed, the now independent Armenia and Azerbaijan began their fight over the stolen region. Neither consider N-K independent but Armenia supports the region financially and militarily. Many attempts to stop the conflict long term have been unsuccessful. To make matters worse, the autocratic Azerbaijani government bans non-nationals from entering the country if their previous visit involved going into Nagorno- Karabakh and their list includes ambassadors, entertainers and foreign politicians!