The process by which porcelain is produced was developed in China during the Tang dynasty 618-907. The Chinese guarded the secret of its manufacture for centuries, but by sometime between 1000 and 1100 the secret had spread to Korea, and by the 1500s to Japan. As early as the 1100s, traders brought Chinese porcelain to Europe, where it was greatly admired. However, it was so rare and expensive that only wealthy people could afford it. In 1708 or 1709 a German chemist named Johann Friedrich Bottger discovered the secret of making hard-paste porcelain. This discovery led to the establishment of a porcelain factory in Meissen in 1710. Meissen porcelain is sometimes also called Dresden because Bottger first worked near that city. For nearly a century, it surpassed in quality all other hard-paste porcelain made in Europe.