Easton's 1897 Bible Dictionary:

Chittim
   or Kittim, a plural form (Gen. 10:4), the name of a branch of
   the descendants of Javan, the "son" of Japheth. Balaam foretold
   (Num. 24:24) "that ships shall come from the coast of Chittim,
   and afflict Eber." Daniel prophesied (11:30) that the ships of
   Chittim would come against the king of the north. It probably
   denotes Cyprus, whose ancient capital was called Kition by the
   Greeks.

     The references elsewhere made to Chittim (Isa. 23:1, 12; Jer.
   2:10; Ezek. 27:6) are to be explained on the ground that while
   the name originally designated the Phoenicians only, it came
   latterly to be used of all the islands and various settlements
   on the sea-coasts which they had occupied, and then of the
   people who succeeded them when the Phoenician power decayed.
   Hence it designates generally the islands and coasts of the
   Mediterranean and the races that inhabit them.