This verse is the closing statement of the table of nations.

These are the families of the sons of Noah: These points back to all the names in 10.2-29, just as These in verse 1 pointed ahead to the same names. Families or “clans” is better translated here by a general term for groups of human beings or, as Good News Translation says, “peoples.” Speiser translates “groupings of Noah’s descendants.” In this context sons of Noah refers to Noah’s sons and their descendants.

According to their genealogies, in their nations: genealogies refers to the history of the line of descent of an individual, family, clan, tribe, or nation from an original pair of ancestors, and here reckoned only as descended from an original male ancestor. According to … nations means classified or grouped together by common descent and by political groupings. Bible en français courant translates “Such were the clans that came from the sons of Noah, according to their lists of descendants, nation by nation.” Biblia Dios Habla Hoy says “These were the clans of the sons of Noah, according to their lines of descent and their territories.” Good News Translation has reversed the order of genealogies and nations to say “Nation by nation, according to their lines of descent.” We may also translate, for example, “All of these groups of people are the offspring of Noah’s sons. Each had its own line of descent and each its own nation.”

And from these the nations spread abroad on the earth after the flood: these points to the families of the sons of Noah at the beginning of the verse. Good News Translation begins with “After the flood,” and many other languages will find this more natural. Spread abroad translates the same verb used in Gen 10.5. Biblia Dios Habla Hoy translates “After the flood they were scattered everywhere and so formed the nations of the world.” New English Bible says “and from them came the separate nations on earth after the flood.” Both of these along with Good News Translation are suitable models for translating.

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Genesis. (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .