The story of Noah in the Bible is one of many such tales from ancient civilizations.  They were mostly written about two thousand years ago, but are usualy from oral traditions going back thousands of years earlier.  The biblical story indicates that rain was the source of the flood, but other stories indicate that rain was only a small part of the flooding and occurred after the initial catastrophe.  In the Book of Enoch, a very old book of Jewish scripture, seven "stars" fall into the sea and cause the seas to rise and flood the land.  This has been interpreted as meaning that a large comet hit earths atmosphere, broke into seven pieces, and the pieces fell into the oceans creating a series of severe tsunamis.  These tsunamis, which may have been thousands of feet high,  flooded much of the land, and, since in those days most people lived near the shores, would have covered nearly all the inhabited land.  Following this deluge, there would have been rapid climate changes, many days of rain, and probably a number of volcanic eruptions.  All of this fits well with the growing evidence of a major disaster that nearly wiped out all life on the planet approximately 10,000 years ago.  It also lends credence to the idea that great civilizations existed twenty, thirty, perhaps even fifty thousand years ago, and were destroyed by this flood, or other earlier disasters.