One Language?

Gen. “11:1 And the whole earth was of one language, and of one speech.”  If this is true then why do these passages from the previous chapter of Genesis say something different?  “Gen 10:5 By these were the isles of the Gentiles divided in their lands; every one after his tongue, after their families, in their nations. Gen 10:20 These are the sons of Ham, after their families, after their tongues, in their countries, and in their nation. Gen10:31 These are the sons of Shem, after their families, after their tongues, in their lands, after their nations.”  After their tongues would refer to different languages in different countries.  I wonder what language the Nimrod's Gentiles were speaking?  Hebrew?