The region was dominated by Bantu-speaking tribes, who built trade links leading into the Congo River basin. Congo-Brazzaville was formerly part of the French colony of Equatorial Africa. Upon independence in 1960, the former colony of French Congo became the Republic of the Congo. The People's Republic of the Congo was a Marxist–Leninist one-party state from 1970 to 1991. Multi-party elections have been held since 1992, although a democratically elected government was ousted in the 1997 Republic of the Congo Civil War and President Denis Sassou Nguesso has ruled for 26 of the past 36 years.
What year was President Denis Sassou Nguesso ousted?  (If the question is unanswerable, say "unanswerable")
unanswerable