It is believed that the Leiths that migrated to Scotland originated from France. The name then being De Leyth. During the Fourteenth Century they appeared around Midlothian and almost certainly took their name from the port at Edinburgh (Leith Port).

William Leith of Barnis was Provost of Aberdeen in 1350, and his descendants acquired and held at various times the lands of Edingarrock, Kirkton de Rain, and New Leslie.

Their appears to have been three separate groups of Leiths' and it is not entirely clear that the Leiths' were in fact a clan in the strict sense of the word.

1.Leith's of Leith Hall. This family married into the Hays family and was subsequently known as Leith-Hays of Leith Hall. This family enjoyed a certain rank of nobility. This line has been researched extensively and it is fairly certain that David Leith's family had no connection to this particular family.

2.Leith's of Harthill. Have not been able to obtain much in the way of information on this line.

3.Leith's of Alexander. This is an offshoot of the Leith-Hay connection and the Sebastian Leith Hays generation migrated to Australia.