People representing Median, Persian, or Saka soldiers at Plataea in 2021 will need trousers. Not everyone needs them: the King rules many lands full of all kinds of men, many of whom have not adopted the Median dress. But reenactors representing men (and possibly women?) from those nations will need them.
One kind of evidence to use is artwork. Aside from the reliefs from Persepolis, the goldsmith’s work from Scythian tombs and the Oxus Treasure, and the mosaic from Pompeii which everyone knows, you will want to have a close look at some of the glazed terracottas of servants from Susa in Forgotten Empire: The World of Ancient Persia or on achemenet and of course at the tomb paintings from Tatarlı, Turkey.
By far the most important archaeological find are the trousers of saltman No. 4 from Chehrābād, Iran, radiocarbon dated to around 405-380 BCE. The saltman is still wearing trousers tucked into his shoes and covered by the skirt of his coat, and all of the textiles are so delicate and salt-encrusted that they cannot be removed, spread flat, and examined. What we know can be summarized in the following few sentences:
- The trousers are woollen, tabby weave, 8 z-spun weft threads per cm, 11 s-spun warp threads per cm.
- There are lateral seams in the trouser legs to ankle, and a vertical slit in the lateral thigh at hip level with the skin of the deceased exposed underneath. (Whether the seams are at the medial leg (inner thigh) or lateral leg (outer thigh) is not clear to me)
- A red woollen thread is sewn along the side seams hiding them except at the slit.
- Overall, they strike the excavators as loose and baggy.
There is no published information about stitches, thread, or dye of saltman 4’s trousers (the cloth looks natural white to me). Edit: Dr. Grömer describes the trousers and tunic as “made of a sturdy, plain natural white woollen cloth” (aus robustem einfarbig naturhellem Wollstoff bestehend).