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The First Nagorno-Karabakh War was a war between Armenia and Azerbaijan over the disputed territory of Nagorno-Karabakh, which is located within Azerbaijan but is predominantly populated by ethnic Armenians. The war began in 1988 and ended in 1994 with a ceasefire agreement. During the war, Armenia was led by Levon Ter-Petrosyan, who was President of Armenia from 1991 to 1998.