When was Shan Hai Jing discovered? What's in it?

The Classic of Mountains and Seas, which is now circulating, was discovered by Liu Xiu (that is, Liu Xin), who inherited the work of his father's "secretary" in the sixth year (the first six years) of Liu Xin, Emperor Wu of the Han Dynasty, when reviewing the secret books collected by the imperial court. Liu Xiu spoke highly of this book and presented it to the imperial court. Since then, the manuscript has been circulated in the world, with a total of 18 volumes, which are divided into five volumes of Mountain Classic, eight volumes of Sea Classic and five volumes of Wild Classic.