400

Year 400 (CD) was a leap year starting on Sunday of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Stilicho and Aurelianus. The denomination 400 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. It was the 400th year of the Common Era (CE) and Anno Domini (AD) designations, the 400th year of the 1st millennium, the 100th and last year of the 4th century, and the 1st year of the 400s decade.