Genesis 11:10

10 These are the descendants of Shem. When Shem was a hundred years old, he became the father of Arpach'shad two years after the flood;

Genesis 11:10 Meaning and Commentary

Genesis 11:10

These are the generations of Shem
Or a genealogy of the posterity of Shem; not of all of them, only of those of the line which led to Abraham, by which might appear the true line in which the Messiah from Adam through Abraham sprung:

Shem was one hundred years old, and begat Arphexad two years after
the flood;
by which it is pretty plain that he was younger than Japheth; (See Gill on Genesis 10:21) of Arphaxad his son, (See Gill on Genesis 10:22).

Genesis 11:10 In-Context

8 So the LORD scattered them abroad from there over the face of all the earth, and they left off building the city.

9 Therefore its name was called Ba'bel, because there the LORD confused the language of all the earth; and from there the LORD scattered them abroad over the face of all the earth.

10 These are the descendants of Shem. When Shem was a hundred years old, he became the father of Arpach'shad two years after the flood;

11 and Shem lived after the birth of Arpach'shad five hundred years, and had other sons and daughters.

12 When Arpach'shad had lived thirty-five years, he became the father of Shelah;