Xia vs Yuan

Xia

name

  • an ancient dynasty in China. 

  • A surname. 

  • A county of Yuncheng, Shanxi, China. 

Yuan

name

  • The imperial dynasty of China from 1279 to 1368. 

  • A surname from Chinese. 

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