《旧唐书》:“有羊羔生于土中……然其脐与地连,割之则死,唯人着甲走马及击鼓以骇之,其羔惊鸣而脐絶,便逐水草。”元代吴莱《渊颖集》:“西域地生羊,以胫骨种土中,闻雷声,则羊子从骨中生……一云漠北人种羊角而生,大如兔而肥美。”元代刘郁《西使记》:“垄种羊出西海,以羊脐种土中,溉以水,闻雷而生。” “Old Tang book”: “There are lambs born in the soil ... ... However, the umbilical cord with the ground, the cut is dead, the only person with a horse and drums in order to apprehend the lambs and the Unexplanation, Aquatic plants. ”Yuan Dynasty Wu Lai“ Yuan Ying set ”: “ Western terrestrial sheep to soil in the tibia, the smell of thunder, then the sheep from the bone ... ... Such as rabbits and plump. ”Yuan Dynasty Liu Yu“ West to remember ”: " Ridge sheep out of the West Sea to sheep umbilical soil, irrigation with water,