The book of Enoch chapters 6 & 7 discuss the 200 (fallen) angels, the sons of heaven taking wives of the daughters of men, and them bearing giant children. Enoch 6:6 tells us that these fallen angels came down in the days of Jared onto the summit of Mount Hermon. Enoch 1-16 The Fallen Angels  Jared was born 460 years after Adam was created, and he died 1,422 years after Adam was created which means he lived 962 years. So somewhere in that time period beginning 460 years after Adam was created and up to 1,422 years after the creation of Adam the fallen angels came down and procreated giants with the daughters of men.   It was during the great flood of 1656 in Noah's time that every living thing on the earth was destroyed including the giants. These were the "giants in the earth in those days" (meaning in the days of Jared, father of Enoch) in Genesis 6:1-4 which says, "And it came to pass, when men began to multiply on the face of the earth, and daughters were born unto them, That the sons of God saw the daughters of

 men that they were fair; and they took them wives of all which they chose.  And the LORD said, My spirit will notalways strive with man, for that he also is flesh: yet his days ahll be an hundred and twenty years. There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown." Thesewere giants on the Earth in those days beginning with Jared's days, and not at the time of Adam's creation.

And the giants on the Earth "also after that" in the above verse were procreated after the flood because we find reference to them first in Genesis 14:5 as the Rephaim, the Zumin & the Emim, and in Numbers 13:33 during the time of Moses when spies were sent into Canaan, and they saw the giants in the land. Numbers 13:33, "And there we saw the giants, the sons of Anak, which come of the giants: and we were in our own sight as grasshoppers, and so we were in their sight." We also see giants in the Bible up until David's time when Goliath, the giant

was slain by him (1 Samuel chapter 17).

In the book of Genesis, these same (fallen) angels were called the sons of God. However, on the left side of page in the Hebrew Interlinear Bible at gen6.pdf they are called the sons of the Elohim in the book of Genesis. Who are the 

Elohim?  Elohim also created man in his image according to Genesis 1:17 in the Hebrew Interlinear Bible at gen1.pdf

and according to Genesis 5:1 at gen5.pdf  Ephesian 3:9 says, "And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God, who created all things by Jesus Christ:"  "Theo" is the Greek word for God, the Father according to the left side of the page at Scripture4All Interlinear: Ephesians 3  So God, the Father created all things by Jesus Christ, and they both are the Elohim who created the sons of Elohim who were the angels in the book of Genesis who later procreated giants with the daughters of men on Earth.