I believe the account of the Bible, and God said He identifies Himself as the one true God by showing us the end from the beginning which He showed us the whole history of mankind, and said no other person or religion would be able to do that.
I do not know of other stories about the flood, but they would of taken it from the Bible for other nations, and religions tend to do that, or from Noah and his family and it passed down.
There was not a flood before Noah's flood to give account, and there was only one flood in history, so it would come after the fact of the flood for at the flood all people were wiped out except Noah and his family, 8 people, so they would not know of the flood, so it would of passed from them when the nations were divided by Noah's 3 sons, and their wives, so that is how they would know.
And how do they know how long ago they would of written about it, and that is was written before Moses wrote of the flood, and all people were gone except Noah and his family which they would give an account of it.
Also in the account in the Bible the nations were not yet divided in to the nations before the flood, so there were no nations, and kingdoms as of yet to give such an account of a flood prior to Noah's flood.
Assyria and Babylon had not even been a kingdom yet before the flood.
It was at the tower of Babel that came after the flood that God confounded their language, and they separated were scattered and the nations came about, for they were stalemating God's plan for them to replenish the earth.
Also out of Ham, Shem, and Jepheth, came all the different skin colors, which is more than 3 skin colors, and out of Ham came Africans, and Babylonians, and out of Jepheth the Caucasians, and out of Shem the Middle Easterns.
But that leaves red and yellow skin left which would have to come for them, so more than one skin color came from the sons.
So God probably changed their DNA when He confounded their language for the different skin colors to divide them in the nations, which this happened after the flood account in the Bible, and not before it.
So there was no Babylon and Assyria before the flood account in the Bible.
That is if a person believes the account of the Bible, and I believe it was passed down from Noah and that is how they knew, and then other cultures decided they wanted to copy the account of the Bible, which would come from Noah and his family, and told by Moses.
Because in reality, and the truth, and all that is holy, it is people that do not follow the Bible, and the God of Israel, that copy His word, and their account, and not the other way around.
Isa 41:21 Produce your cause, saith the LORD; bring forth your strong reasons, saith the King of Jacob.
Isa 41:22 Let them bring them forth, and shew us what shall happen: let them shew the former things, what they be, that we may consider them, and know the latter end of them; or declare us things for to come.
Isa 41:26 Who hath declared from the beginning, that we may know? and beforetime, that we may say, He is righteous? yea, there is none that sheweth, yea, there is none that declareth, yea, there is none that heareth your words.
Isa 41:28 For I beheld, and there was no man; even among them, and there was no counsellor, that, when I asked of them, could answer a word.
God already told us the whole history of mankind, and said no other person will be able to do the same, so I am believing God's account of the flood, for the word of God tells us of Him, and creation, and the flood, and the nations being divided, and the nation of Israel coming about, and so forth until the time now, and for the future.
But the world would like to say that the Bible copied stories of other religions, and people, to discredit them, especially at this time when the world is going away from God, which He said they will rebel against Him one day when the nations come together and are giving heed to the new age movement.
Which God warns us of the new age movement that will occur at the latter times which is now, and their false interpretation of the Bible based on the occult, and evolution, and people are still evolving to be greater and spiritual provided by the New Age Christ.
Which the New Age Christ will establish peace in the Middle East between Jews and Palestinians, and then work as a man of peace in the world, and push the new age movement in the world to prepare the world to accept him when he claims to be God by evolving through nature, and there is no personal God.
Which science is making ridiculous claims of things they can never know, and discover, to try to make evolution appear true, and the Bible account seem false, which God said do not believe science so falsely called.
It is all part of the deception today to support evolution, and discredit the Bible, and there is a God.
Did the Bible get this story from other religions, or people, but they did not, for the Bible says none of the wicked shall understand, but the wise shall understand, so those that would try to discredit the Bible do not know about what the Bible is saying concerning this time frame, and are doing and believing how God said they would do.
The new age movement is the future for this world, and God already told us about it, and the man of sin who will claim to be God and go against all people that oppose him.
But God is allowing him to do it so He can end sin on earth.
Jesus said there would be much deception at the end time, so they will want to discredit the Bible.
Why do you think they took prayer out of school and started teaching evolution, and science confirms it, for that is their religion in the future.
Everyone that does not want to believe in the God of the Bible, and follow Him, will follow the New Age Christ and will not be able to resist it.