u/-BlackKaiser-

Eastern Han dynasty

Any thoughts on the time period?

Almost 120 cm long
Edit: Many wondered the authenticity of this sword due to its perfect surface. I will explain a bit, this one is heavily grind down, around 2mm, I got this from an older collector, and he got it decades ago, some collectors preferred perfect surface back then due to the influence of Japanese swords. Usually I'd prefer it in its original shape, but It's already grind down to this degree when I got it, I simply removed the original handle collar and commissioned sharpening and shirasaya, I don't know how to edit photos but I've post them in the comments. I'm a bit skeptical before removing the collar and sharpening, but relieved seeing there is no trace of welding, and the patterns indicates although it's heavily grind down, the loss of metal is acceptable considering its size and thickness. This happens a lot in Nihonto Koto as well, as the profile changes after generations of resharpening.
Another contributing factor is that war sword of this period tend to have thick and wide profile, which is meant for multiple times of sharpening in the first place. The tang, the original collar, the remains of wrapping fibers on the tang, the shape of the ring pommel all indicate that this is from 420-690 ad( pictures in the comments)

Western Han dynasty

Norishige則重, ranked as 特別保存(specially preserved) by NBTHK. Norishige studied under Shindō Go Kunimitsu where he trained alongside Yukimitsu and Masamune, mastering the Sōshū tradition. His jigane (base steel) is a masterful combination of irons of different hardness, producing a distinctive hada (grain pattern) with strong activity of jigei (ground streaks). Reminiscent of pine bark, this texture has been called “matsukawa hada” since ancient times and is a unique feature not seen in other smiths.

Norishige則重, ranked as 特別保存(specially preserved) by NBTHK. Norishige studied under Shindō Go Kunimitsu where he trained alongside Yukimitsu and Masamune, mastering the Sōshū tradition. His jigane (base steel) is a masterful combination of irons of different hardness, producing a distinctive hada (grain pattern) with strong activity of jigei (ground streaks). Reminiscent of pine bark, this texture has been called “matsukawa hada” since ancient times and is a unique feature not seen in other smiths.

A restored Tang dynasty Dao, around 1200 years old

Western Han dynasty，the steel quality must be very good to support such a slim profile, four continuous "victory " symbols on the tang, symbolizing an unbroken string of wins.

A interesting example that's in rare and excellent condition, a comparison of before and after restoration at the end, double fuller and a false edge, the "habaki" has some bronze inlays remaining