Kiev vs Kievan Russia

Kiev

name
  • A former principality in Europe. The medieval principality centered on Kiev; the Kievan state or Kievan Rus. 

  • The government of Ukraine. 

  • A city, the administrative centre of Kyiv oblast, capital city of Ukraine. 

  • A province, an oblast of Ukraine. Seat: Kyiv. 

Kievan Russia

How often have the words Kiev and Kievan Russia occurred in a corpus of books? (source: Google Ngram Viewer )