How many people were alive before the flood? According to the Chronicles of Jerahmeel, a 12th-century Hebrew chronicle translated by undefined Gaster in 1899, an exact census was taken 640 years after Noah left the ark. The total population descended from Noah's three sons was precisely 714,100 fighting men—not counting women and children.
The text provides a detailed breakdown. The descendants of Japheth—Gomer, Magog, Madai, Yavan, Tubal, Meshech, and Tiras—produced 142,000 warriors under their prince Pinhas. The largest Japhethite clan was Kittim at 18,300; the smallest was Gomer at 5,800. The descendants of Ham vastly outnumbered them. Under their prince Nimrod, the Hamites numbered 492,000 valiant men. The sons of Canaan alone counted 32,900, while the clan of Sabtecha reached 46,400.
The chronicle traces an intricate genealogy from Noah's sons through to Abraham. Through Shem came Arpakhshad, then Shelah, then Eber, from whom two lines branched: Peleg (in whose days the earth was divided) and Yoktan. From Peleg came Re'u, who prophesied that in four generations a child would arise "whose throne will be established on high"—"a perfect righteous man, the father of a multitude of nations." From Re'u came Serug, then Nahor, then Terah, and finally Abram, Nahor, and Haran.
But the world was already darkening. In those generations, the inhabitants of the land began practicing astrology, divination, and passing their children through fire. Only Serug and his sons refused to walk in those ways. Noah himself witnessed all of this. He lived 350 years after the flood, dying at the age of 950—long enough to see the very corruption he had survived begin again.