1120 (MCXX) was a leap year starting on Thursday of the Julian calendar, the 1120th year of the Common Era (CE) and Anno Domini (AD) designations, the 120th year of the 2nd millennium, the 20th year of the 12th century, and the 1st year of the 1120s decade. As of the start of 1120, the Gregorian calendar was 7 days ahead of the Julian calendar, which was the dominant calendar of the time.