Leukai, according to Diodoros, was founded by the Persian admiral Tachos in 352 BCE. He also mentions that it was originally located on a crag by the sea. However, after he left the cities of Klazomenai and Kyme argued over who should take possession.
After some disputes, the resolved that the god (presumably Apollo, who was later worshipped in Leukai) should decide who takes possession. An oracle decreed that it would be whoever first sacrificed in Leukai, so each was to start in their own city and race to Leukai to make the sacrifice.
The Klazomenians figured that they would have a strong advantage, since their city was far closer, but the Kymeans played a trick. They founded another city close to Leukai, set out from there, and won. Thereafter, they held a festival to honor the feat.
Strabo described it as a small town. The location today is in a restricted zone and not visitable, though research there has indicated not much remains of the city.