Original sentence: In the Book of Jubilees, Magog is mentioned as a son of Noah's son Japheth to whom land is allocated, while Gog is a region on Japheth's borders
Edited sentence: The Book of Jubilees, composed about 100 BCE, is essentially a revised version of Genesis 1-Exodus 14; Magog is mentioned as a son of Noah's son Japheth to whom land is allocated, while Gog is a region on Japheth's borders