The starting point for anyone interested in the history of Highland dress is

Old Irish & Highland Dress

by H F McClintock

W Tempest, Dundalgan Press, Dundalk, 1943.

This exhaustively covers bits of costume recovered from bogs, surviving examples of Highland dress in museums, the iconography, etc etc.

I kept seeing this title crop up in the bibiographies of various books on Highland dress and I decided I needed to read the source.

Matt has the greatest hands-on experience with early kilts and tartans I know of.