The fabric tartan is closely associated with modern Scotland, and has such a cultural significance that using the word can be tricky. BBC Scotland recently aired a documentary showing what it claims could be the "first-ever depiction of tartan", or at least the earliest surviving depiction.
In the third century CE Roman Emperor Caracalla fought the Caledonians and liked to think of himself as having conquered them, and a statue of him once stood high in Volubilis, a city in Morocco. Part of this statue survives (or, at least, part of a statue), it's from a cloak, and it shows what people believe is a Caledonian warrior, complete with what the BBC called tartan. The BBC has a picture, and some quotes, but to many experts, such as Adrian Murdoch, all they see are patterned trousers with very little to link it to Scot's tartan. Murdoch's blog goes into more details.