In the beginning God created the heaven and the earth. And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.
…[A]nd God divided the light from the darkness. And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.… And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.… And God saw every thing that he had made, and, behold, it was very good. And the evening and the morning were the sixth day.
The generations from Adam to Abraham are 20. Mind you, they are extraordinary generations spanning nearly 9,000 years. And some people say it's 18 generations and 4,000 years.
The beginning of the world on these accounts is somewhere in the early to mid Neolithic culture.
At first our fathers were beholden to idols. Then the Omnipresent brought us close to His worship, as it is written: And Joshua said to the whole of the nation, so says the Lord, God of Israel: Your fathers settled on the far side of the river forever ago … and they worshipped other Gods. And I took your father, took Abraham, from across that river, and I walked him through the whole land of Canaan. And I made plentiful his seed, and I gave him Isaac. And I gave Isaac, Jacob and Esau. And I gave Mount Seir to Esau as a legacy. And Jacob and his sons went down to Egypt.
Blessed is the One Who Preserves his pledges to Israel, blessed is He. For the Holy One, Blessed is He, envisioned the end of an era in order to do as he told our father Abraham in the Covenant of the Pieces; as it is written: And He said to Abraham, Know and keep knowing that your offspring and he tortured by them for four hundred years. Know also that I will stand in judgment of their enslavers, and in the wake of that judgment your people will go out with great wealth.
….The Aramean disappeared my father, and he went down to Egypt, and lingered there with a small group. And it was there he transformed us into a great nation, massive and many. …. And we cried out to the Lord, God of our fathers, and the Lord heard our voices, and He saw our torture and our toil, and the great pressure upon us. And the Lord lifted us out of Egypt in the might hand of an outstretched arm, with an awesome spectacle, with signs and undeniable wonders.
This teaches us, it was there that Israel became exceptional, distinguished through mitzvoth—distinct as a nation unto itself. Neither suspected of unchastities, nor of noxious talk. And they did not pervert their names, and they did not pervert their language.
In every generation, a person is obligated to view himself as if he were the one who went out from Egypt, as it is said: And on that day tell your son, saying “For this purpose the Lord labored on my behalf, by taking me out of Egypt.” It was not our fathers alone who were deliverd by the holy One, Blessed is He—we are also delivered with them, as it is said: And He took us out from there in order to bring us—to us!—the land that He pledged to our fathers.
 From Foer and Englander, New American Haggadah.