Bark cloth has been made in China since at least 8,000 BCE. The oldest recorded reference to screened paper containing mulberry fibers is
Cai Lun's
rag paper,
Cao Huo paper, from 105 CE. The technique of using new
bast fibers was in production in China by the 3rd century
AD and spread to north and east where the
Moraceae plants were growing (
Thymelaeaceae plants were also used). Mulberry paper became the preferred writing material under the
Song dynasty. In
manuscript paper, pure mulberry content usually indicates Chinese (or even more Eastern) origin, as this is where the mulberry trees could be found at a time: while plants were also growing in
oases along the
Silk road, it was much more profitable to use these for cultivating the
silkworms. As a result, in regions to the west of China,
rag paper technology kept being used. == List of mulberry papers ==