The Germanic word *frankon- "javelin" was borrowed into Latin as Francus, to refer to the Franks, the Germanic tribes of the Rhine region who conquered Gaul circa 500. Francus became Old French Franc, and was borrowed into Old English as Franca and frensisċ, eventually becoming France and French.
*frankon- is also found in Frank from Old English Franca. The first OED citation is from Beowulf, "In Francna fæðm", "in the grasp of the Franks."
In the 10th century, the Old French Franc was borrowed into Arabic as faranji, where it was used to refer to European traders. This was possibly borrowed into Persian as farangi, and then into Hindi-Urdu as farangī (फ़िरंगी فرنگي?), romanized as firangi, ferengi or feringhee, where it is a derogatory term for foreigners. The Hindi-Urdu word would seem to be where the creators of Star Trek the Next Generation got the name of the Ferengi race. (But wikipedia cites the liner notes of a Banco de Gaia album as the source of this.)