1 Chronicles does not mention the geographic spread of the various groups in the repopulation of the world after the flood. From Genesis we learn that the descendants of Japheth migrated to what is now known as southeastern Europe and Turkey. The Japhethites as a whole are considered to be the ancestors of the Indo-European peoples.1
Japheth had seven sons, but the descendants of only two of them, Gomer and Javan, are named. The descendants of Japheth do not receive as much attention in the history of Israel as the Hamites and the rest of the Semites.2
Of the geographic locations mentioned, only a few can be recognized with any degree of accuracy. Madai is probably Media, which was closely associated with Persia which is now modern Iran. Javan is Ionia or Greece. Tarshish is recognized as a distant western land, possibly Spain, and was known for its merchandising (Isaiah 23:1; Isaiah 23:14; Ezekiel 27:12, Ezekiel 27:25; Jonah 1:3).
5 The sons of Japheth: Gomer, Magog, Madai, Javan, Tubal, Meshech, and Tiras.