"between Migdol and the sea": There, was their greatness ("gedulathan," as in "Migdol"). There, was their glory and their splendor. There, Joseph had gathered their silver and their gold, viz. (Genesis 47:14) "And Joseph collected, etc."
Between Migdol and the Sea There, Was Their Greatness
Mekhilta Tractate Vayehi Beshalach 2:4