The farthest back that I have researched my Duarts is to Northern Ireland, with John Duart born 1784.  Duart Castle, on the Isle of Mull, in Scotland is where I believe the Duarts originated, but have not found proof, only family lore.  I set out to prove this link, but get stuck in Hillsborough, County Down, Scotland.

According to Renaissance of the Clan MacLean Comprising also a History of Dubhaird Caisteal and the Great Gathering on August 24, 1912, by J.P. MacLean, Ph.D. written in 1913, "the Dewart family should also be recognized (as part of the clan MacLean), which is descended from Big Dewar of Balemartin, Tiree, the first man from Mull who ever settled in that isle.  He fled from Mull owing to his having given information to the MacLean of Lochbuy, which was injurious to the chief.  His name was John MacLean, but was called Dewar (Diurach).  He and his seven sons were powerful men, and held the township of Balemartin, including Sorabi.  Several of his descendants still live in Tiree, and are known as na Diuraich, Those living in the United States take the name of Dewart and are well know for their respectability and high standing and are ardent clansmen."

DNA testing would most likely help with identifying where this family began.  I have tested with AncestryDNA, Family Tree DNA and my mother, tested with Living DNA.  To date we have not had matches that have been helpful.  If you would consider possibly submitting your DNA to this ONS study, it would be greatly appreciated.