niqab vs yashmak

niqab

noun
  • A veil which covers the face, worn by some Muslim women as a part of sartorial hijab. 

yashmak

noun
  • A veil worn by Muslim women to cover parts of the face when they are in public. 

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