The Septuagint tells us that Job was the son of Zare and that he was the fifth generation from Abraham.
"And he himself was the son of his father Zare, one of the sons of Esau, and of his mother Bosorrha, so that he was the fifth from Abraam". We will trace this genealogy from Abraham.:
                                                                ABRAHAM
HAGAR (wife of Abraham) (Gen.16:3)                 SARAH wife of Abraham) (Gen.17:15)

ISHMAEL (firstborn son) (Gen.16:15)                  ISAAC (promised son) (Gen.17:19) - Generation I

BASEMATH (daughter of Ishmael)    married     ESAU (firstborn son of Issac) (Gen.36:3)- Generation II

                                      REUL (son of ESAU and BASEMATH) (Gen.36:4) - Generation III

                                      ZERAH (son of REUL) (Gen.36:13) - Generaton IV

                                      JOB (son of ZERAH) (Septuagint-Job 42:17d) - Generation V

       Abraham (name meaning - the father of multitude) was born in Ur Mesopotamia, and died at age of 175 in Hebron. Abraham was descendent of Shem, the son of Noah and ancestor of Semites.
According to Islam, Christianity and Judaism - the three major religions and 3/4 of world population, Abraham was elected by God to become a father of many nations and a carrier of His plan for humanity.
The Bible Genesis 12 reads:
"1 The LORD had said to Abram,..." 2 "I will make you into a great nation, and I will bless you; I will make your name great, and you will be a blessing. 3 I will bless those who bless you, and whoever curses you I will curse; and all peoples on earth will be blessed through you."
God also said to Abraham, Genesis 15:
"Do not be afraid, Abram. I am your shield, your very great reward"... "Look up at the sky and count the stars - if indeed you can count them."... "So shall your offspring be."... "To your descendants I give this land, from the Wadi of Egypt to the great river, the Euphrates."
Abraham was a father of eight sons who become ancestors of many nations. Job was descendent of his two sons, Ishmael and Isaac.
Link to search for historical Abraham.

Sarah was the wife of Abraham and the mother of Isaac as described in the Hebrew Bible and the Quran.
The Hebrew name Sarah indicates a woman of high rank and is sometimes translated as "princess".
Sarah and Abraham had no children. Abraham, however, prayed to God for a son.
Sarah, being barren, subsequently gave him her Egyptian handmaiden Hagar, to wed as his second wife.
Hagar bore Ishmael, when Abraham was 86.
Thirteen years later, God announced to Abraham, now a hundred, that barren Sarah would give birth to a second son, Isaac. Sarah became pregnant and bore a son to Abraham in his old age, at the very time God had promised him.
Sarah lived to be a hundred and twenty-seven years old. She died at Kiriath Arba (Hebron) in the land of Canaan.

Ishmael was Abraham's first born child. His name is translated literally as "God has hearkened", suggesting that a child so named was regarded as the fulfillment of a divine promise.
The name was used in early Babylonian and in Minaean cultures.
Bible - Genesis 17 reads: " 1 And when Abram was ninety years old and nine, the LORD appeared to Abram, and said unto him"... "20 And as for Ishmael, I have heard thee: Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly; twelve princes shall he beget, and I will make him a great nation. " Genesis 25 continues :" 13 And these are the names of the sons of Ishmael, by their names, according to their generations: the firstborn of Ishmael,":
Nebaioth, Kedar, Adbeel, Mibsam, Mishma, Dumah, Massa, Hadad, Tema, Jetur, Naphish, Kedmah and Princess Bashemath, a daughter of Ishmael, who married Esau - son of Isaac.
Bashemath and Esau, the firstborn son of Isaac, were the Grate-grandparents of Job.
..."16 These are the sons of Ishmael, and these are their names, by their towns, and by their castles; twelve princes according to their nations.... 18 And they dwelt from Havilah unto Shur."
From archaeology, Ishmael is known as Ishme-Dagan and was the fourth king in the First Dynasty of Isin - according to the Sumerian king list. He was the son in-law of Iddin-Dagan and ruled ca. 1889-1871 BC. and was succeeded by his son in law - Lipit-Eshtar / Esau. Link to search for historical Ishmael.

Isaac,("he will laugh"), was the only son Abraham had with his wife Sarah. He was the father of two sons, founders of two nations: Esau the firstborn, called later Edom, and Jacob renamed as Israel.
Bible - Genesis 17 reads: "1 When Abram was ninety-nine years old, the LORD appeared to Abram and said to him, "I am Almighty God; walk before Me and be blameless. 2 And I will make My covenant between Me and you, and I will make nations of you, and kings shall come from you. 15 Then God said to Abraham, "As for Sarai your wife ... I will bless her and also give you a son by her; ... and she shall be a mother of nations; kings of peoples shall be from her." " ... Sarah your wife shall bear you a son, and you shall call his name Isaac; I will establish My covenant with him for an everlasting covenant, and with his descendants after him. " Abraham was 100 years old when Isaac was born to him. When Isaac was forty years old he took Rebekah, a granddaughter of Abraham's brother Nahor, as wife. Isaac pleaded with the LORD for his wife, because she was barren; and the LORD granted his plea, and Rebekah conceived. But the children struggled together within her; and she said, "If all is well, why am I like this?" So she went to inquire of the LORD. And the LORD said to her: "Two nations are in your womb ... " So when her days were fulfilled for her to give birth, there were twins in her womb. The firstborn was named Esau, and after him came out his tween brother, with his hand grasping Esau's heel; so he was named Jacob. Isaac was sixty years old when Rebecca bore them, and Isaac loved Esau.