March 11, 1985. Mikhail Gorbachev is named General Secretary of the Communist Party of the Soviet Union. Under his leadership, the USSR would collapse, and with it, the countries of Armenia and Azerbaijan, then part of the USSR, would become independent countries.
The Nagorno-Karabakh region was part of Azerbaijan, but, majority Armenian. It was an Autonomous Oblast, the same as Chechnya, and thus had special rights. Some in the USSR suggested it could become a part of any Independent Armenia.
The area had a long history, and was fought over after WW1 between the newly independent countries of Armenia and Azerbaijan, until Azerbaijan got the upper hand and gained control over the area.
During this period an important even happened called the Shusha massacre. The town, labeled on Google Maps as "Şuşa" or, as I will call it for the remainder of this post, Susa, was partly inhabited by Armenians, revolted, and as a result, Azerbaijani troops began killing Armenians in the city. At least 500 were killed.
Eventually both nations would be annexed by the USSR, and the conflict became frozen in time.
February 20th, 1988, leaders of the soviet (council) of Karabakh voted to join Armenia.
March 10th, 1988, Gorbachev announces the borders would not change (and thus, Nagorno-Karabakh would remain in Azerbaijan)
From this point on, low-level conflict would be present in the entire area.
December 27th, 1991, Soviet troops withdraw from the area.
February 26th, 1992, the Khojaly massacre takes place. It saw up to 500 Azerbaijanis killed by Armenians.
February 27th, 1992. Armenian forces capture the city of Susa.
May 5th, 1994. Ceasefire is called.
The war, however, did not end.
2008 - Martakert clashes
2010 - Clashes in a wider area, but in Martakert as well.
2012 - Additional clashes occur, including clashes on the Azerbaijani-Armenian border outside of the disputed zone
2016 - Heaviest clashes to date occurred.
This is where we enter the current conflict. Constant clashes occurring with occasional flare ups.
August 4th, 2020. A massive blast rocks Beirut. More than a thousand Armenians from the city are re-located to the disputed zone.
September 27th, 2020, an Azerbaijani invasion of the disputed zone begins.
Note that I've included two maps showing the area. One is from the Soviet Union from before WW1, where I've drawn the borders, and the other, from a map I've done on Google maps.
This would be the first time the boundaries would move since the 90s. Azerbaijan proceeded to push back the Armenians.
Many Ceasefires would be called and broken, but that would all end in November.
November 9th, 2020. Azerbaijani forces take Susa.
This put an end to the war, at least, for now. Not only does Susa have importance to both Armenia and Azerbaijan, but, it lies on the main road connecting the area to Armenia.
It is unclear if this will lead to a lasting peace or not, but, what is clear, is that the new boundary better matches what both sides agreed to at Prague, with the largest change being Azerbaijani control over the southern portion of Nagorno-Karabakh, and the total evacuation of Armenian troops of areas between the Nagorno-Karabakh and Armenia.
It is thus likely that this will more or less lead to an end to the conflict. The only remaining question and point of possible future violence, is what happens to the new Nagorno-Karabakh (the area in orange on the google map). Should a free and fair referendum be held, even if all Azerbaijani refugees from the area return, it is quite clear the result would be joining with Armenia. Azerbaijan, however, may pack the area within the black line, but south of the orange line, with Azerbaijani citizens, and demand the area as a whole vote; or, it may simply block any vote at all and demand the area permanently remain part of Azerbaijan. Either would likely spark a renewed conflict for the region.
Regardless, the war, for now, is over.