dervish vs sadhu

dervish

noun
  • Any irregular guerrilla fighter resembling the Sudanese Mahdi in equipment, uniform, tactics, etc. 

  • A citizen or inhabitant of Darawiish (circa 1895–1920 C.E.), an anti-colonial polity in modern Somalia headed by Sufis. 

  • One of the followers of Muhammad Ahmad, the Mahdi of the Sudan, in the 1880s. 

sadhu

noun
  • An ascetic or practitioner of yoga (yogi) who has given up pursuit of the first three Hindu goals of life: kama (enjoyment), artha (practical objectives) and even dharma (duty). 

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