Well, there’s a lot there. The original drew on 70s/80s martial arts films mostly (Japanese/US ninja films and Shaw Brothers kung fu) and of course the state of the medium has moved on. Here are some media which are both authentic and well known:
- Crouching Tiger Hidden Dragon (2000): Not really very recent but the best and most famous distillation of the wuxia genre for this century.
- Shogun (2024): As mentioned above, for Sengoku Japan.
- Alchemy of Souls (2022): Probably the best known Korean medieval fantasy series, comes with lots of worldbuilding and Korean fantasy tropes, available on Netflix. Basing Koryo on this series would be absolutely fine by me.
- The Untamed (2019): A relatively well known Netflix xianxia drama, with the bonus of being very gay (danmei). There are loads of these, though.
- The Apothecary Diaries (2023): A Japanese anime series set in a mixed (mostly Ming Chinese but also quite Japanese and Korean) East Asian medieval setting, also on Netflix.