The various stories of Conan the Barbarian occur in the fictional "Hyborian Age", set after the destruction of Atlantis and before the rise
of the known ancient civilizations. This is a specific epoch in a fictional timeline created by Howard for many of the low fantasy tales
of his artificial legendary.
The reasons behind the invention of the Hyborian Age were perhaps commercial: Howard had an intense love for history and historical
dramas; however, at the same time, he recognized the difficulties and the time-consuming research work needed in maintaining historical
accuracy. By conceiving a timeless setting — "a vanished age" — and by carefully choosing names that resembled human history, Howard
shrewdly avoided the problem of historical anachronisms and the need for lengthy exposition.
According to "The Phoenix on the Sword", the adventures of Conan take place "...Between the years when the oceans drank Atlantis and
the gleaming cities, and the years of the rise of the Sons of Aryas..." -Wiki-