The Old Testament starts out in the book of Genesis with the creation of the heavens and earth.
In the beginning God created the heaven and the earth”, Genesis 1 (KJV):
In chapter 1 there are six days of creation, but note what a day is to the Lord. 8 But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day, 2 Peter 3:8 (KJV)
1 “Thus the heavens and the earth were finished”, Genesis 2:1 (KJV)
Man (Adam) is placed in the Garden of Eden and given a woman as a mate, Genesis 2:7-23:
Adam an Eve eat from the tree of knowledge of good and evil and are expelled from the Garden of Eden, provoked by the serpent, Genesis 3:23
Next is the Patriarchal Age which lasted for centuries until it ended, Genesis 5. Men lived up into the 900s, not much is revealed how God communicated with the Patriarchal age. Noah and the flood, brought on by The “wickedness of man, Genesis 6: and Genesis 7.
The tower of Babel, Genesis 11:
The language is confused in Genesis 11, because there was only one nation and they wanted to build a tower, whose top may reach unto heaven and make a name for themselves, indicating unnecessary power. Verse 6 indicates with only one nation there wouldn’t be another to stop them from drifting into an unwanted controlling type government. So by confusing the language they disperse the area, settling elsewhere.
Introduction of Abraham, Genesis 12:
Abram originally came from Ur of the Chaldees. God changes Abrams name to Abraham and his wife Sarai to Sarah, Genesis 17. They have a son Isaac who in time has two sons Esau and Jacob.
The lineage of Christ is passed through Jacob. Jacob as time passes has twelve sons. Jacobs name is changed to Israel by God, and as time passes over the course of 500 years Moses leads the children of Israel out of Egypt, Exodus 14.
The Jewish Dispensation probably begins in the book of Exodus 19:3, where Moses goes up on Mount Sinai, after 400 years of captivity in Egypt. A nation is born after 40 years of wandering in the wilderness and The twelve sons of Israel become the twelve tribes of Israel.
From Moses and the start of the Jewish Dispensation to its decline and end is around 1500 years.