I have been asked about the riding outfit of the Achaemenid Great King Cyrus the Great , hence I decided to do a little entry on the so called Median Cloak - kandys or kantuš, that essentially it was a riding coat of the Persians and ... the Eurasian steppe horsemen.
But first about Cyrus or rather his tomb, for it is a list of garments and weapons found there when Alexander entered the tomb, some 200 years after Cyrus' death (Persian clothing in general ), according to the Arrian's depiction of the Cyrus tomb (Anabasis, 6.29.6) - which in my opinion is the closest depiction on the Great King riding costume (via one of the best books on the reconstructed Achaemenid Persian army by prof. Sekunda and illustrator Simon Chew) :
there we have: a kandys (Median cloak), tunics of Babylonian workmanship and some other tunics, Median anaxyrides (pants); colors of these garments - hyacinth(dark blue) and purple, and perhaps yellow (from saffron); neck torques (gold), akinaka (short swords), earrings of gold. Therefore, I daresay he would not wear the Elamite/Persian robe when mounted. On his head he would wear a form of a Persian hood (tiara or kyrbasia) or kitaris, perhaps bound with a blue diadem with a white decoration (from Curtius' description in Historiae Alexandri Magni)
Kandyses from Persepolis
Encyclopedia Iranica has a nice entry on the subject but in it strongly disclaims any connection between etymology of 'kantus' and Polish-Hungarian 'Kontusz' in their entry on 'candys' - so it may be so in etymological sense but clearly there is a connection between the Polish-Hungarian garments and Median kandys.
Sergey Yatsenko, in his work ''Costume of the Ancient Eurasia (the Iranian-Speaking Peoples)'' Moscow 2006, writes that kandys was a long garment with sleeves longer than one's arms (sleeves like the Hungarian hussar jacket), that it had a turn down collar, and it had a pair or ribbons or strings at the neck/collar to tie it up on one's chest or shoulders. Sleeves of the Persians seemed to have been narrow whereas the sleeves of the Saka/Scythian kandys/riding coat were wide (vide UkokPlateau)
Furthermore dr Yatsenko writes that kandys was an ancient Indo-Iranian garment, and the ancestors of the Persians already had a special, thicker, parade-like fur coat. Persian riding coat seemed to have been a thinner one, a cloak with sleeves. But is was a garment worn by the Persian kings and warriors/nobility at hunt and at war (as described by Xenophon ).
Oxus treasure, they had the entire front lapels decorated with fur, while around the neck there was a hood or a collar. They wore kandys hanging it off the shoulders, with ribbons or strings tied in front, holding it on one's trunk. Light purple kandys might have been the particular king's coat.
Datames who is thought to have reformed the Persian army in IV BC century.
So called Alexander Sarcophagus of Sidon:
Kandys is visible in the Partian art eg coins of various Parthian kings, we know from the description of Carrhae battle that the eventually victorious Parthians and Sarmatians fighting for Rustam Suren that they had coats (perhaps leather ones) to cover their armor.
Commagene king's kandys
Bahram II and figures wearing coats fastened with clasps
Sassanian grafito from Persepolis - showing a kandys on a horseman( more coats in the link to Calieri's article)
Roman riding coat from Egypt VII century AD
some primary sources (websites in the links) for the Achaemenid era: