0s BC is usually considered the last decade of the 1st century BC and the 1st millennium BC. However, like the 0s, the number of years in the 0s BC is not always clearly defined. Note that there is no year zero (0) in either the proleptic Gregorian calendar or Julian calendar. Hence 1 BC is followed by the year AD 1.
AD 1 is the first year of the Anno Domini era (also known as the Common Era). In 525 (the consulship of Probus Junior Flavius Probus), a Christian monk named Dionysius Exiguus stated that the incarnation of Jesus occurred 525 years earlier. Whether Dionysius regarded "incarnation" as Jesus' birth or conception, and whether Dionysius placed it in 1 BC or AD 1 are debated by modern scholars. Nevertheless, these same scholars believe Jesus was actually born a few years earlier, during this decade.
This article concerns the period 9 BC – 1 BC, the last nine years before the Anno Domini era, not the last ten years.