I recently just bought a samurai sword from a estate sale and im trying to identify when it was made. I removed the handle to look for markings on the tang and i found this paper. The tang is covered in dark brown rust, and this paper was sitting on the tang, there is a area on the tang were you can see where this paper had been sitting for some time.. i don't see any visible markings on the tang itself, but im not a expert. any help i would greatly appreciate!