FAL said:
Then I would tell you that the kilt wasn't used back then
It's a typical example of 'invented' tradition, if I am not mistaken.
Yes, quite invented. When Gaels initially emerged in Ireland, they didn't wear kilts, but trousers and shirts, or robes, or knee-length shirts, depending on their societal rank. This continues through most of Gaelic history, though designs and fashions do change.
The kilt emerged in the Western Isles, and is only definitely described toward the end of the 16th century. It wasn't a common garment. It was actually originally the Gaelic cloak, the brat, made larger and heavier. In battle, it'd be wrapped around the body as it was too cumbersome to fight in wearing normally, and looked more like a robe originally. The kilt went through several phases, but was predominant mainly only among the northernmost clans of the Scots originally; not even all highlanders wore it. The kilt was banned by the Dress Act in 1746, and that was lifted in 1782. The Celtic Society of Edinburgh encouraged its wear calling it 'ancient Highland dress'; truth is, it's not that old. It was in the 19th century it really caught on among Scots in both highlands and lowlands, as well as the Scottish diaspora.
The earliest 'Scots' are out of time frame, but would dress and largely appear as the Gaelic Irish did, and they themselves actually considered themselves Irish for some time; Robert Bruce even tried to gain support for his campaigns, and his brother Edward as king of the Irish, by refering to Ireland and Scotland as 'our country'; a single entity. Kind of funny, Robert and Edward had Norman names, and lived in the lowlands of Scotland, which closer resembled the French or English, mostly, rather than the Irish (as the highlanders did), though Robert was lord of Carrick, a Gaelic region of the lowlands, like Galloway was. His mother was Gaelic Scot, his father was a Norman Scot, and he dressed in some account as the Irish did. Freemen would generally be wearing a knee-length shirt and a short cloak detailing their station by number of colors (the color and pattern had nothing to do with clan ties, though it was often plaid; 'tartan' is actually later than kilts), and usually boots or shoes, and no trousers. Trousers were worn by laborers, and often Gaelic soldiers of any station in English employ. Nobility would wear both the knee-length shirt, as well as more complex robes, and larger, more complex cloaks.
Picts don't exist in this period. Picts are a confederation of Caledonian tribes born out of resistance to the Romans, and probably combined with British refugees and settlers from Ireland (the 'invasion' of the Dal Riatans seems less plausible lately; more likely Gaels had been settling in Argyle for some time, either ignored or allowed by the Caledonian-then-Pictish leadership). Caledonians would be dressed like other Britons mainly; trousers, shirts, leather vests, things like that. Many would fight half or fully nude.
