The sea water rose significantly covering almost the entire land mass.
SHIPS FROM ALL OVER THE WORLD WITH POWERFUL AND INFLUENTIAL PEOPLE set sail in order to wait for this flood to recede. However this journey continued for about 2.5 lac years. Several hundreds of generations of survivors, as such, spend the life over water, and with the help of Matsya Avatar also survived the onslaught of extreme conditions.
Slowly with the phenomenal rise of water levels, the sea water also became stationary .All the turbulence and so called churning of water was gone. The water became still, very still. This was never witnessed by mankind before. Even sea life started slowly vanishing .They were at the end of the kalp. Please read for further details: MATSYA AVTAR IN LIGHT OF GEOGRAPHICAL CONDITIONS
As of today, the Dharm lay down by Lord Ram and Lord Krishna need to be followed. But, unfortunately, no one tells us what the dharm is.
However human civilization has always been cruel on other beings. They started exploiting these two legged animals as slaves, and as animals. They refused to recognize them as human beings although they were now developing into same. The exploitation was cruel and inhuman to say the least. Here was the first batch of human beings of the new kalp-very pure and innocent (Aryans as one would like to call them in Sanskrit), and the batch of survivors of the older kalp-whose antecedents were not known, were torturing them instead of welcoming them.