John Gills Exposition of the Bible Commentary - Genesis 10:5
By these were the isles of the Gentiles divided in their lands ,.... That is, by those sons of Japheth before mentioned; and by "isles" are meant, not countries surrounded with water, for the isles in this sense would not have been sufficient for the posterity of Japheth; nor can it be thought they would leave the continent, where there was room enough for them, and go into islands; and besides must have found it difficult to get there, when shipping and navigation were little known: but it... read more
Matthew Henry's Complete Commentary - Genesis 10:1-5
Moses begins with Japheth's family, either because he was the eldest, or because his family lay remotest from Israel and had least concern with them at the time when Moses wrote, and therefore he mentions that race very briefly, hastening to give an account of the posterity of Ham, who were Israel's enemies and of Shem, who were Israel's ancestors; for it is the church that the scripture is designed to be the history of, and of the nations of the world only as they were some way or other... read more