Yawan in ancient Hebrew, denoting Ionia (cf. Josephus. Also see Herodotus 7:94). Other sources state that Yavan is Macedonia (Targum Yonathan; Yoma 10a, see note on Genesis 10:2, 'Madai'). Others translate it as Ovisos (Yerushalmi, Megilla 1:9), denoting Ephisus, an ancient Greek city in Lydia, founded by the Ionians around 1050 b.c.e. An ancient source states that Yavan lived on the islands and the shore of Lydia (Yov'loth 9:10), where indeed the Ionians lived.
