As I understand it, scale armour, such as the Sassanid Iranian cataphract units wore, required some sort of padding under it. In Europe, a gambeson was used for this purpose, and also served as the only armour of poorer soldiers who could not afford mail.
What was used in the Sassanid empire? As I understand it, the gambeson is a very warm garment - not fit for the warmer Middle-eastern climate. Nor could I find any record of it being used this far south. (It is possible I did not look hard enough, or in the right places.) But if not the gambeson, what was used?