Archeaology tells us that there were continuous societies throughout this period in China, Africa, Egypt, Mesopotamia, Europe, South America and so on.
How is it possible that these numerous societies comprised of diverse races existed throughout the time period of the flood when all but Noah and family were supposedly wiped out.
what i would say is that we need to look for evidence of the flood account in those very ancient civilisations. The fact is we do find such evidence that those civilizations do have legends of a similar event. If none of those civilizations had such legends, then perhaps we'd need to ask why, but the fact that they do have the same stories indicates that their ancestors were aware, or were at least deeply affected, by such a story.
Manu is the character in the Hindu myth found in the Satapatha-Brahmana.
“In the morning they brought to Manu [mankind’s ancestor and first lawgiver] water for washing . . . When he was washing himself, a fish [Vishnu in his incarnation as Matsya] came into his hands.
“It spoke to him the word, ‘Rear me, I will save thee!’ ‘Wherefrom wilt thou save me?’ ‘A flood will carry away all these creatures: from that I will save thee!’ ‘How am I to rear thee?’”
The fish instructed Manu on how to care for him. “Thereupon it said, ‘In such and such a year that flood will come. Thou shalt then attend to me (to my advice) by preparing a ship; and when the flood has risen thou shalt enter into the ship, and I will save thee from it.’”
Manu followed the fish’s instructions, and during the flood the fish pulled the ship to a “northern mountain. It then said, ‘I have saved thee. Fasten the ship to a tree; but let not the water cut thee off, whilst thou art on the mountain. As the water subsides, thou mayest gradually descend!’”—
Utnapishtim is the flood survivor mentioned in the Akkadian Epic of Gilgamesh. He is the one who tells Gilgamesh the story of the flood. As found in Epic tablet XI, known as the Flood Tablet, Utnapishtim recounts instructions given to him concerning the flood:
“Tear down (this) house, build a ship! Give up possessions, seek thou life. . . . Aboard the ship take thou the seed of all living things.”
Yü is the survivor of the flood in Chinese myths called “Period of the Great Ten”. He is said to be an ancient ruler of China who was
“the conqueror of the Great Flood. Yü channeled flood waters into rivers and seas to resettle his people.” Some have noted the similarities in the old Sumerian king list because this myth speaks of an age where 10 emperors/kings ruled until there was a great flood which which brought in a new era.
Ziusudra is the survivor mentioned in the Sumerian myth about the flood. He is described as a pious, a god-fearing king.... and the Babylonian and Assyrian civilizations, which came later, were influenced by the Sumerians so there are links.
the South American Aztec mythology spoke of four previous ages, during the first of which the earth was inhabited by giants. (That is another reminder of the Nephilim, the giants referred to in the Bible at Genesis 6:4.) It included a primeval flood legend in which “the waters above merge with those below, obliterating the horizons and making of everything a timeless cosmic ocean.” The god controlling rain and water was Tlaloc. However, his rain was not obtained cheaply but was given “in exchange for the blood of sacrificed victims whose flowing tears would simulate and so stimulate the flow of rain.”
the Maya in Mexico and Central America had their Flood legend that involved a universal deluge, or haiyococab, which means “water over the earth.”
So we can find evidence that these cultures may not be as old as the flood because in all these legends the flood wiped out those who lived before them. According to their accounts, their civilizations are founded 'after' the event. And we need to also consider that the dating of such cites may not necessarily be accurate.
The fact that these stories are being retold by 'seemingly' unrelated nations may be evidence that these nations are not as 'unrelated' as we might think.
Even if the date is off by hundreds of years it is still not possible for genetic diversity and to have created these different races in such a short period of time. Some cultures such as the Sumerians and Egyptians are continuous from 3500 BC (no gap where everyone was wiped out).
you are looking at it from the perspective that these civilisations existed before the flood happened and that just may not be correct. When a civilization is just starting out, it usually starts with only a small group of people...not a 'civilization' as such... cities would have began as small compounds with only a cluster of camps. The genesis account says that Cain built a 'city' when he was sent away with only his one wife.
What if these civilisations developed after the flood? Then we would not expect to see a gap in their existence but we certainly would expect to see their legends and myths include that story.... and that is exactly what we find.
