Shield of Skudra

[Vladimír Dlhý]

Achaemenid reliefs from Apadana in Persepolis depict delegates from Skudra satrapy - Thracians. They bear unusual shields different from pelta shields or any other we traditionally associate with Thracians.  Shields are shown from profile. We can clearly see vertical rows reminding spiral construction of kalkan or chinese rattan shields. There are also some shields made by reenactors from straw instead of wicker, but with same structure. I don't know any other depiction of this type of shield from ancient times.
Could the ancient Thracians use this type of shield already in the antiquity, predating the medieval asian wicker shields?