The first Sumerian king Alulim, at Eridu, is described as reigning for 28,800 years, followed by several later kings of similar periods.In total these antediluvian kings ruled for 241,200 years from the time when "the kingship was lowered from heaven" to the time when "the flood" swept over the land.
Once these cultures developed calendars, many began to ponder the question of precisely how long ago this event happened.
The standard ancient Sumerian King List (WB 444) lists various mythical antediluvian kings and gives them reigns of several tens of thousands of years.
Another ancient date for the start of the mythikón (mythical) period is found preserved in Augustine's City of God xviii.3, which dates it to 2050 BC.
Very few ancient Greeks or Romans attempted to date the creation, or beginning of the ádelon (obscure) period.
Ovid, however, dated the start of the (mythikón) period to the reign of Inachus, who he dated 400 or so years after the flood of Ogyges, meaning around 1900–1700 BC, but agreed with Varro that the mythikón ended during the first Olympiad (776 BC).
See Ages of Man for more details about Ovid's chronology.
According to Herodotus the ancient Egyptian demigods began 11,340 years before the reign of Seti I (1290 BC), so 11,340 1290 = 12,630 BC, while he listed earlier figures, 15,000 and 17,000, for the reign of the gods. Schwaller de Lubicz, however, in his work Sacred Science, reconstructed these dates to conclude that the ancient Egyptians dated their creation to an astronomical (stellar) event some 30,000 years before Herodotus' own time.
These figures were discussed by Isaac Newton in his The Chronology of Ancient Kingdoms Amended (1728) but were dismissed as fabrications. The ancient Greek writer Diodorus Siculus wrote that the ancient Egyptians dated their creation (or start of their reign of Gods) "a little less than eighteen thousand years" from Ptolemy XII Auletes (117–51 BC).
The ancient Greeks reported similar figures on ancient Egyptian chronology.
Diogenes Laertius recorded that the ancient Egyptians dated their creation to their first god Hephaestus, who by interpretatio graeca was Ptah....
A man can scarcely believe them (Babylonians) for they reckon that, down to Alexander's crossing over into Asia, it has been four hundred and seventy-three thousand years, since they began in early times to make their observations of the stars.