Rakushun explains the origins of Mt. Hou/Taishan in chapter 38 of Shadow of the Moon. (Taishan is also one of the "Five Great Mountains" of China.) The function of the yaboku and why one is a good place to spend the night is covered in chapter 53. Rakushun uses a suugu (on loan from Rokuta) in A Thousand Leagues of Wind.
A "blue bird" is essentially a bird-based dictation machine. See "Pen-Pals" from Dreaming of Paradise.

Rikou is featured in "Kizan" from Dreaming of Paradise. He observes that Kyou has had a stable dynasty for ninety years, and later that Youko recently published her Imperial Rescript abolishing kowtowing, which comes at the end of A Thousand Leagues of Wind. This suggests that Tonan no Tsubasa takes place roughly ninety years before the present.

Labels: 12 kingdoms, tonan