Avar? or Kirghiz? Rock Carving at Seljek, Siberia
Figure 31a, Oriental Armour by H. Russell Robinson
A rock carving at Suljek in Siberia, probably representing an armed Avarian horseman, shows the conical helmet with Roman cheekguards and a long coat of lamellar armour with short sleeves.
The lamellae are represented by rows of short vertical lines, the same convention as that used on a silver dish in the Hermitage at Leningrad showing an eighth-century Turkish horseman (Fig. 31B).
David Nicole (referencing Khudyakov) in Attila and the Nomad Hordes writes that it is Kirghiz, 11th-12th century. i.e. Yenisei Kyrgyz.
Referenced on p6, MAA 89 Byzantine Armies 886-1118 by Ian Heath & Angus McBride:
Avar horseman from a 6th century rock carving.
Much byzantine military equipment was copied from the Avars in the 6th-7th centuries, including clothing, stirrups, horse-armour, and the widespread use of lamellar.
Avar Heavy Cavalry from Armies of the Dark Ages 600-1066 by Ian Heath based on the Seljek, Siberia, carving.
Petroglyphs at Baga Oigor, Turkic Period 7th-9th century, also with crenelated mane on their horses.
11th century Illustrations of Costume & Soldiers