Abernethy is a name which has been around much longer than the Leslie name. It combines two Celtic words 'Aber' which means confluence and 'Nethy' which is the name of the river which joins the Earn and then drains into the Firth of Tay. Abernethy is an ancient Pictish place which, in the 4th century, was the center for the now Christian Southern Picts. In 460 A.D. the King of the Picts, Nechtan, granted some of the land in this area to build a church. In 850 A.D. Gartnaidh, then King of the Picts, had built another church in the area where the famous Round Tower was built. This round tower is now one of only two remaining Celtic structures left in Scotland. The tower was left in hereditary right to the Culdees (Celtic Clergy) who would later become the lay abbots and lords of Abernethy. In the 12th century the last of the lay abbots, Ethelred, became a secular peer.
Ethelred's great grandson, Orm, greatly increased the Abernethy holdings by obtaining grants of land from Scotland's King William The Lion. Lawrence was a counselor to King William and was also one of the guarantors of the Treaty of 1189.
Lawrence's grandson, Sir Hugh De Abernethy, was involved in the kidnapping of King Alexander III. Hugh was later pardoned for the abduction. After King Alexander III died at age 45, the kingdom was out of control. The regent was the Earl of Fife. Hugh, along with his two sons Patrick and William along with Sir Walter Percy were involved in the assassination of the Earl of Fife. Sir Walter Percy was captured and executed for the murder. Sir Hugh and his son William were also caught and sent to prison where they both died, and Patrick, the killer, managed to escape and fled to France where he ended his days.
The Abernethy barony was passed down to Sir Hugh's son Alexander who was an avid supporter of the fight to maintain Scotlands independence from England. When Edward I became King of England Alexander changed his views and became a supporter of the English. For this he was appointed the warden of the area between the Firth of Forth and the Highlands. Alexander, under the order of King Edward II, was sent to Rome to gain the favor of the Pope against the Scots. It was a failed attempt. Scotlands King Robert Bruce then declared all of Alexander's lands to be forfeited due to Alexander's disloyalty. And, since Alexander had no male heir, all of his holdings went to his three daughters Margaret, Helen, and Mary. Margaret married the Earl of Angus. Helen married the Earl of Crawford, and Mary married the 6th Baron of Leslie, Sir Andrew. With the marriage of Sir Andrew and Mary Abernethy the Leslies acquired the baronies of Ballinbreich and Cairney, which were some of the most important of the Abernethy estates. Also, Clan Leslie gained Abernethy and Cairney as septs to the Clan. The third son of the marriage of Sir Andrew and Mary was John. John was the direct ancestor to the Earl of Rothes.
The baronial title was later given to William, a descendant of Patrick Abernethy. The title continued with Sir Lawrence Abernethy who became Lord Saltoun. The 9th Lord Saltoun died in 1688 without an heir which ended all ties to the ancient Abernethy line. Although the name continues and is still found in Scotland, the United States, England, and many other countries, all lines to the first Abernethys no longer exist. The name continues today through the descendants of cadet families.