The International Standard Bible Encyclopaedia has a very useful article on 'Kittim', from which I will now quote:
1. Two Usages of the Name:
In #Ge 10:4 the word is applied to the descendants of Javan, and indicates, therefore, the Greek-Latin races, whose territory extended along the coasts of the Mediterranean, and included its islands.
By the side of Kittim are mentioned Elisha, Tarshish, and Dodanim ( = Rodanim of #1Ch 1:7), generally explained respectively as Sicily with Southern Italy, Spain and Rhodes.
]In its narrower sense Kittim appears simply to have stood for the island of Cyprus — it is mentioned between Bashan ( = Pal) and the isles of Elisha in #Eze 27:6,7, and with this #Isa 23:1,12 agree, Kittim occurring in these passages between Tarshish, Tyre and Sidon.
Like the word 'Tarshish', the word 'Kittim' is clearly used in a broad sense, whilst also having certain narrower applications.
The comment on Genesis 10:4 is noteworthy, since it demonsrates that one of the principal identities of 'Kittim', is 'the Greek-Latin races
', a matter related directly to our understanding of the use of the word in Daniel 11.
Once again, Genesis 10 shows its importance as a control text in this issue of determining the identity of certain nations.