Jian'an 22 (建安二十二年)
The 22nd year of the Jian'an reign period of the last Han emperor.
217 CE
Discourse on Epidemic Qi, and a Brother's Letter
Cao Zhi and Cao Pi, quoted in the Taiping yulan (Imperial Readings of the Taiping Era), chapter 742 · 217 or soon after (the essay, on the epidemic of Jian'an 22); 218 (Cao Pi's letter)
[1]
建安二十二年癘氣流行
In the twenty-second year of the Jian'an era [217], a pestilent qi spread through the land.