These are the generations {k} of Shem: Shem was an hundred years old, and begat Arphaxad two years after the flood:

(k) He returns to the genealogy of Shem, to come to the history of Abram, in which the Church of God is described, which is Moses' principle purpose.

Wesley's Notes

11:10 Observe here, That nothing is left upon record concerning those of this line, but their names and ages; the Holy Ghost seeming to hasten thro' them to the story of Abraham. How little do we know of those that are gone before us in this world, even those that lived in the same places where we live! Or indeed of those who are our contemporaries, but in distant places. That there was an observable gradual decrease in the years of their lives. Shem reached to 600 years, which yet fell short of the age of the patriarchs before the flood; the three next came short of 500, the three next did not reach to 300, and after them we read not of any that attained to 200 but Terah; and not many ages after this, Moses reckoned 70 or 80 to be the utmost men ordinarily arrive at. When the earth began to be replenished, mens lives began to shorten so that the decrease is to be imputed to the wise disposal of providence, rather than to any decay of nature. That Eber, from whom the Hebrews were denominated, was the longest lived of any that were born after the flood; which perhaps was the reward of his strict adherence to the ways of God.

Scofield Reference Notes

[1] generations of Shem

Genesis 11. and 12. mark an important turning point in the divine dealing. Heretofore the history has been that of the whole Adamic race. There has been neither Jew nor Gentile; all have been one in "the first man Adam." Henceforth, in the Scripture record, humanity must be thought of as a vast stream from which God, in the call of Abram and the creation of the nation of Israel, has but drawn off a slender rill, through which He may at last purify the great river itself. Israel was called to be a witness to the unity of God in the midst of universal idolatry Dt 6:4 Isa 43:10-12 to illustrate the blessedness of serving the true God Dt 33:26-29 to receive and preserve the divine revelations Rom 3:1,2 Dt 4:5-8 and to produce the messiah Gen 3:15 21:12 28:10,14 49:10 2Sam 7:16,17 Isa 4:3,4 Mt 1:1.

The reader of scripture should hold firmly in mind:

(1) that from Gen 12. to Mat 12.45 the Scriptures have primarily in view Israel, the little rill, not the great Gentile river; though again and again the universality of the ultimate divine intent breaks into view (e.g. Gen 12:3 Isa 2:2,4 5:26 9:1,2 11:10-12 42:1-6 49:6,12 Isa 52:15 54:3 55:5 60:3,5,11-16 61:6,9 62:2 66:12,18,19 Jer 16:19 Joel 3:9,10 Mal 1:11 Rom 9. 10. 11. Gal 3:8-14.

(2) that the human race, henceforth called Gentile in distinction from Israel, goes on under the Adamic and Noahic covenants; and that for the race (outside Israel) the dispensations of Conscience and of Human government continue. The moral history of the great Gentile world is told in Rom 1:21-32 and its moral accountability in Rom 2:1-16. Conscience never acquits: it either "accuses" or "excuses." Where the law is known to the Gentiles it is to them, as to Israel, "a ministration of death," a "curse" Rom 3:19,20 7:9,10 2Cor 3:7 Gal 3:10. A wholly new responsibility arises when either Jew or Gentile knows the Gospel Jn 3:18,19,36 15:22-24 16:9 1Jn 5:9-12.

Matthew Henry's Concise Commentary

11:10-26 Here is a genealogy, or list of names, ending in Abram, the friend of God, and thus leading towards Christ, the promised Seed, who was the son of Abram. Nothing is left upon record but their names and ages; the Holy Ghost seeming to hasten through them to the history of Abram. How little do we know of those that are gone before us in this world, even of those that lived in the same places where we live, as we likewise know little of those who now live in distant places! We have enough to do to mind our own work. When the earth began to be peopled, men's lives began to shorten; this was the wise disposal of Providence.