According to ancient records, Chi You, the lord of Jiuli, was the ancestor of short soldiers. Fighting with the Yellow Emperor, he was defeated in the "Valley of Fierce Li", and his head was missing. Later, the people of Jizhou dug up the ground and found Chi You's bones, which were "as indestructible as copper and iron".
... Hmm... Actually, the text has nothing to do with the legend... I am just semi-illiterate and control over settings.