emporium vs trading post

emporium

noun
  • A city or region which is a major trading centre; also, a place within a city for commerce and trading; a marketplace. 

  • A business set up to enable foreign traders to engage in commerce in a country; a factory (now the more common term). 

  • A shop that offers a wide variety of goods for sale; a department store; (with a descriptive word) a shop specializing in particular goods. 

trading post

noun
  • A place where trading of goods takes place. 

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