Kosal Dev Singh was the grandson of Anangpal Tomar, the last Hindu - Rajput king of Delhi, and the son of Ausan Singh. According to the Haryana State Gazetteer, Singh founded Kosli, a large Yaduvanshi Ahirs village in 1193 A.D. He was said to have met a sage engaged in meditation at Kosli, then under dense shrub jungle.
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