When did mikhail Gorbachev rule?

Answer 1

One cannot answer the question "When did Gorbachev rule?" in the same vein as "When did Peter the Great rule" or "When did Stalin rule?" Mikhail Gorbachev was neither a monarch nor a dictator. There is an article on Wiki Answers, answering the question "When did Gorbachev become the leader of the Soviet Union?", see link below.

That said, Mikhail Gorbachev was in power from March 1985, when he became the General Secretary, until December 1991, when Soviet Union ceased to exist.