Asano stamped nagura versus not?

Gents, I bought a Koma the other day from Aframes. He has a good reputation here, so this question is not about him, but it's more about history.

The koma I bought does *not* have the Asano stamp. It does, however, have the very interesting aspect of clearly being pre-industrial. The asano stamped meijero, tenjo, and botan stamped naguras I have are all clearly 'post' industrial: smoothed sides. One of them does have one side that was not totally smoothed, and that little facet was clearly cut with a rotary tool. As was the non-asano stamped 'chu' I have.

This'n, on the other hand, has only one smoothed side (where the stamps are) and that side was smoothed much. All the other sides were clearly cut either with a really coarse toothed saw, or with some axelike implement of destruction. I'm voting for the saw because the marks look very much like the same marks rough cut green lumber takes on when cut with one of the gigunda 18'th century japanese greenwood ripsaws.

So...the question is....how long has the asano stamp been around? Does it have pre-industrial provenance, or is it a post-industrial creation?