1991 (MCMXCI) was a common year starting on Tuesday of the Gregorian calendar, the 1991st year of the Common Era (CE) and Anno Domini (AD) designations, the 991st year of the 2nd millennium, the 91st year of the 20th century, and the 2nd year of the 1990s decade.

1990 (MCMXC) was a common year starting on Monday of the Gregorian calendar, the 1990th year of the Common Era (CE) and Anno Domini (AD) designations, the 990th year of the 2nd millennium, the 90th year of the 20th century, and the 1st year of the 1990s decade.