Roman use of the Contus

[Frank]

Also the development of Cataphracts and later Medieval Knight tactics, should this be credited to Sarmatians, Persians, Germans or the Romans themselves?

Between Cataphracts and Medieval Knights are about 500 years of development. So i would not like to credit ancients that much for medieval warfare, even if there are relations.

The first roman cataphract ala was founded in the early 2nd century in Moesia. Most probably it should counter sarmatian forces. So yes, the iranian steppe tribes should receive our credit. Also the Parthians were steppe tribes before they invaded Parthia. Even the Persians came perhaps from these northern steppes, but more than 500 years earlier.

The interesting question is, why the romans adopted this style that late and not latest after Charrae.

I have no clue, which origins the greek heavy cavalry had, but the romans obviously adopted the sarmatian/parthian style.

The germans are mixed. The western german tribes were not that cavalry heavy, even if they had good cavalry, but rather the classic type. But the Goths had a strong heavy cavalry, which they probably established after contact with the sarmatians. So again the iranian steppe tribes.