The Nagorno-Karabakh conflict has been a complex, long-standing ethnic and territorial dispute between Armenia and Azerbaijan, with significant developments occurring over decades. Here's a summary of the key events:

Historical Background: Nagorno-Karabakh, known as "Artsakh" by Armenians, is a region internationally recognized as part of Azerbaijan but was populated predominantly by ethnic Armenians. During Soviet times, it was an autonomous oblast within the Azerbaijan SSR. The conflict's roots trace back to the late 1980s when the region sought to join Armenia as the USSR was collapsing.
First Nagorno-Karabakh War (1988-1994): This war resulted in Armenian forces, with support from Armenia, gaining control over Nagorno-Karabakh and seven surrounding Azerbaijani districts. It ended with a ceasefire in 1994, but no peace treaty was signed, leaving the situation unresolved.
Intermittent Clashes: Despite the ceasefire, there were numerous skirmishes and escalations over the years, including a significant flare-up in April 2016 known as the "Four-Day War."
Second Nagorno-Karabakh War (2020): Full-scale war erupted again in late September 2020, lasting 44 days. Azerbaijan, with military support from Turkey, managed to recapture significant territories around and within Nagorno-Karabakh. A Russian-brokered ceasefire on November 9, 2020, ended the conflict, with Russian peacekeepers deployed to monitor the situation.
Post-2020 Developments:
Blockade and Humanitarian Crisis: In December 2022, Azerbaijan effectively blockaded the Lachin corridor, the only road connecting Nagorno-Karabakh to Armenia, leading to a humanitarian crisis with shortages of food and medicine. Azerbaijan denied blockading but claimed it was due to protests against illegal mining.
2023 Offensive and Disintegration of Nagorno-Karabakh: On September 19, 2023, Azerbaijan launched a military operation described as an "anti-terrorist" measure. Within days, the local Armenian forces surrendered, leading to the dissolution of the Republic of Artsakh. By the end of September 2023, an exodus of nearly all the 120,000 ethnic Armenians from the region occurred, effectively ending the de facto independence of Nagorno-Karabakh. 
Current Status: As of the latest updates, Nagorno-Karabakh has been reintegrated into Azerbaijan, with promises from Baku to protect the rights of remaining Armenians. However, there are concerns about ethnic cleansing due to the mass exodus of Armenians. International reactions have varied, with calls for humanitarian aid and protection of the rights of the displaced.

This summary reflects the situation based on available information up to the specified date. The conflict remains a sensitive issue, with ongoing discussions about the rights of the displaced Armenians, peace agreements between Armenia and Azerbaijan, and the broader geopolitical implications in the South Caucasus region.