Boling vs Ding Prefecture

Boling

name
  • A former region of early imperial China in present-day Hebei. 

  • A former commandery of medieval China in present-day Hebei. 

  • The various seats of the commandery: present-day Raoyang, Anping, and Dingzhou in Hebei. 

  • A surname. 

  • A former princely title of imperial China. 

Ding Prefecture

How often have the words Boling and Ding Prefecture occurred in a corpus of books? (source: Google Ngram Viewer )