Why does the Torah not specify the names of the cities that the children of Mitzrayim built, like it does with regard to the other families?
Ramban: It is not necessary to do so, since (a) the land of Mitzrayim itself (which is named after the father) is well-known, and (b) all his children lived around Mitzrayim (or even in it), and their respective lands were all called after them (as was Pelashes).
Ramban (citing the Ibn Ezra): All the names mentioned here, are in fact names of countries, 1 each one inhabited by one specific family.
Since the Torah uses the word "mi'Sham" (from there), which denotes location.
QUESTIONS ON RASHI
Rashi writes: "Lehavim - their faces were similar to a flame (Lahav)." Mizrachi asks - Why does Rashi interpret only this name?
Gur Aryeh: When we find that the name of a person has a clear meaning, we may assume that he would not be so named unless there was a connection to that meaning.
