New kilt in an older style

[Pleater]

The long plaid is basically the simple, most ancient form of the Roman toga, even before the ends were curved.
The folds under the arm were used as pockets, called a sinus, spread for carrying fruit, for instance, or tied with a loop of cord for small valuables and the toga was - in far antiquity - worn over a loincloth and considered the mark of a Roman citizen.

Only later was a tunica added, maybe made from something more washable than the woollen toga and the band of coloured decoration rose from the lower to the upper long edge of the fabric as worn.
Over time the length also increased so it was wound elaborately - and was probably made of linin rather than wool - far easier to keep clean and not so insulating nor so heavy when it had become yards and yards of fabric.

If you wanted to know the rank of an ancient Roman you'd look down, to the type of sandal and colour of the decorative stripe.

The folds of the military drummer's plaid are made very precisely - I think they must be sewn in, and then it is drawn very tight to the body and trapped under belts etc.
When worn more casually it is useful as it can be drawn closer or pushed aside according to the need of the wearer.

Anne the Pleater