Silk production began in China during the Neolithic era. Specifically, it was discovered by members of the Yangshao culture in the 4th millennium BC. Over time, silk was used for everything from clothing and writing to denoting social class (particularly during the Tang Dynasty) as well as for many other applications. Silk was exclusive to China until the Silk Road opened during the latter half of the 1st millennium BC. For another thousand years after that, China maintained a monopoly on silk production. Around 300 AD, silk production spread to Japan. By 522 AD, the Byzantines had obtained silkworm eggs and had begun making silk, too. As sericulture (silk farming) spread, Chinese silk exports became less important, although they still dominated the luxury market. Silk production was introduced to Western Europe by the Crusades and soon after, many Italian states developed successful silk industries and began exporting the material to the rest of Europe. In the 16th century, France developed a successful silk industry as well. The Industrial Revolution brought major changes to Europe’s silk industry. As cotton became cheaper, silk production became less mainstream because it was more expensive to produce. However, new weaving techniques made the silk production that was still taking place more efficient. Then an epidemic of silkworm diseases hurt production, and some industries, including France’s silk economy, never recovered. In the 20th century, China and Japan regained their dominance in the silk market; China is once again the world’s largest silk producer. However, modern fabrics such as nylon have reduced the demand for silk, so it is once again considered a luxury good.