sentences:  Esfarayen is the most important Persian-speaking town and locality of far northwestern Khurasan.The surrounding mountains and deserts have become totally Kurdish and Turkmen in their ethnicity and language.It was only Esfarayen that resisted the flood of violence that swept away the ancient and sedentary Persian speaking farmers and town folks of northern Khurasan, starting with the Mongol invasion, coming of the destructive tribes, and finally the massive murder and depopulation of northern Khurasan in the 18th and 19th centuries in the hands of Turkmen raiders and slave catchers.