Question: when were the months of the year created

title: History of calendars
text: For chronological purposes , the flaw of the Anno Domini system was that dates have to be reckoned backwards or forwards according as they are BC or AD . According to the Catholic Encyclopedia , `` in an ideally perfect system all events would be reckoned in one sequence . The difficulty was to find a starting point whence to reckon , for the beginnings of history in which this should naturally be placed are those of which chronologically we know least . '' For both Christians and Jews , the prime historical date was the Year of Creation , or Annus Mundi . The Eastern Orthodox Church fixed the date of Creation at 5509 BC . This remained the basis of the ecclesiastical calendar in the Greek and Russian Orthodox world until modern times . The Coptic Church fixed on 5500 BC . Later , the Church of England , under Archbishop Ussher in 1650 , would pick 4004 BC .