It is narrated from Sayyiduna Imran bin Husayn and Sayyiduna Samurah bin Jundub (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "Three sons were born to Nuh (peace be upon him): Sam, the forefather of the Arabs; Ham, the forefather of the Abyssinians; and Yafith, the forefather of the Romans."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15400