Sarmatian origins of the spatha?

[Robert Vermaat]

Yet it wasn't until the influx of Sarmatian (and here I mean "Alanic")recruits that we find the longer sword in regular service. And here, too, it may be likely that the native spatha, more like a jian, actually, was coveted over the lesser tempered ones produced in the fabricae. (Recent evidence points to these steppe weapons being made of folded steel, based on newer techniques of metal analysis.)

I was under a strong impression that the cavalry used the spatha long before any Alanic recruits entered the Roman army?
Any information available as to the metallic contstruction of Roman spathae, compared to steppe weapons?