What is the oldest clan Scott tartan?

Well see when I watched Star Trek my favorite character was Scotty, and in this one episode he wore his grey Scottish kilt for making some sort of diplomacy with alien foreigners, along with Kirk, and Spock (who wore the diplomatic uniform). And since tartans back then didn't get to the Lowlands until the 17th century or 16th century (where the Scotts were a border clan and had territories in the Lowlands), I was wondering if the Scott's Grey tartan sett was one of the most oldest tartans.