He was born in Guiyang (桂陽) during the Eastern Han Dynasty, and became a paperwork secretary (中常侍) of Emperor Hedi. For papermaking, he tried materials like bark, hemp, and even fishing net. He was imprisoned (for an unrelated matter) and committed suicide in prison.
While paper is widely used worldwide today, the creator of this extremely important invention is little-known outside East Asia. Cai invented paper in AD 105. It immediately became widely used in China. In 751, some Chinese paper makers were captured by Arabs after Tang troops were annihilated in the Battle of Talas River. The techniques of paper making then spread to the West.