Sword moving from right to left

[Flavivs Aetivs]

Doesn't a painting at dura europus show soldiers with round shields and mail coifs too though?

Sure, and most of the shields found at Dura were oval. But I meant that rectangular shields were apparently being used as well at that date, which suggests that the change in shield and/or sword arrangement cannot be determined as a single point, but must allow for at least half a century of variations.

That's what I was trying to say - Dura is an example of where they were being used at the same time.