Comment by Sukotto

Screenwriters for "Conan the Barbarian" (1982) might have got it from Part 2, Chapter XI of "Genghis Khan The Emperor Of All Men" by H. Lamb (1936).

https://archive.org/details/genghiskhantheem035122mbp/page/n...

  One day in the pavilion at Karakorum he asked
  an officer of the Mongol guard what, in all the
  world, could bring the greatest happiness.

  "The open steppe, a clear day, and a swift horse
  under you," responded the officer after a little
  thought, "and a falcon on your on your wrist to
  start up hares."

  "Nay," responded the Khan, "to crush your enemies,
  to see them fall at your feet -- to take their 
  horses and goods and hear the lamentation of 
  their women. That is best."