who changed the calendar from bc to ad
Anno Domini This calendar era is based on the traditionally reckoned year of the conception or birth of Jesus of Nazareth, with AD counting years from the start of this epoch, and BC denoting years before the start of the era. There is no year zero in this scheme, so the year AD 1 immediately follows the year 1 BC. This dating system was devised in 525 by Dionysius Exiguus of Scythia Minor, but was not widely used until after 800.[9][10]
Tiberius Tiberius (/taɪˈbɪəriəs/; Latin: Tiberius Caesar Divi Augusti filius Augustus;[1][2] 16 November 42 BC – 16 March 37 AD) was Roman emperor from 14 AD to 37 AD, succeeding the first emperor, Augustus.
My Ántonia
Gregorian calendar The Gregorian calendar is internationally the most widely used civil calendar.[1][2][Note 1] It is named after Pope Gregory XIII, who introduced it in October 1582.