Everything God created six thousand years ago and more, when He made the world, He creates all of them together right now, Eckhart said in an epoch when six thousand gave people the impression that give us a billion years.
Paschal Annals estimate as the year of creation 5509 b. C. Dionysius Petavius summarizes the relevant Byzantine estimations of the Creation to three: 5493, 5501 and mainly 5509 (cf. De Graecorum aeris ac computis dissertatio, Patrologia Graeca 19.1395). Newton believed that the world was created in 4004 b. C., Kepler at the 27th of April (!) 4977 b. C.; Galileo knows 5600 years of world life; Such estimations did not stop until the 19th c, i.e. after the geological investigations of the 18th c naturalists.
The root of those Creation accounts is in Biblical genealogies, which, however, do not count scientifically, but they symbolize the coherence of world history as a history of divine origin. Thus the issue was not of much interest to the Greek Fathers. We can recall the characteristic response of Patriarch Photius of Constantinople, who detested Origen’s relevant research.
Start and End refer mainly to personal realities, not to diary data. St Basil the Great writes about the Days of Creation that, whether we say 7 days or 7 ages, it is exactly the same. Yet, the estimations that we saw were not indifferent to people at large, precisely because they are connected with the Bible. This interest was increasing as history approached the year 7000 from the Creation of the world, i.e. 1491 A.D.
The symmetry of a 7 Days Creation and 7 millennia of history, especially when Byzantium was falling, made the two seem related. St Symeon of Thessaloniki (15th c) speaking about such rumors, emphasizes what is important, like previous Fathers did, and naturally, i.e. without being provocative with this calmness, which testifies to the spiritual strength of Byzantium at a time when it was entering the storm of the Islamic occupation.