Why Tang dynasty China, around 750

Liuyan needed a world with roads, so I gave her the Tang.

China around 750 is enormous and in motion: trade routes running out past the frontier, a cosmopolitan capital, and between the safe places, a great deal of country where the law is whoever is standing in it. That is the gap a blade for hire exists in. Her work is real in that world, not a fantasy grafted on, and the research kept giving me its texture: the way distance was measured in days of walking, what an inn on a trade road actually offered, what a stranger's posture told you before their mouth did.

It suited her because Liuyan's discipline is not a philosophy. It lives in her body, and the Tang road tests a body honestly. Nobody out there cares what she feels. They care where her weight sits. Which made it the perfect place to hide a feeling, right up until it stopped hiding.