I'm not 100% sure but my guess is that oil in ancient China was probably pretty scarce. Kanki got his by stealing it from the capital. There's probably not many large reserves of oil that are close enough.
Bachira
2025-10-21 10:38:48 +0000 UTC
inside the siege tower its not stairs, its incline but flat surface that goes around in a square formation. I think in the episode where they used siege tower last time we saw the inside more clearly and it was not stairs