《北史·列传·卷八十七》
山里有洞穴，洞穴里有平坦的土地，茂盛的青草，方圆数百里，四面都是山。
山有洞穴，穴内有平壤茂草，周迥数百里，四面俱山。
There was a cave in the mountains, and inside the cave was flat land with lush grass, covering an area of hundreds of miles that was surrounded by mountains on all sides.