"China has been famous for its silk for thousands of years. The main trade route linking China to the West was even known as the Silk Road. The ancient Romans prized Chinese silk and imported both thread and cloth. The Chinese kept their methods of silk production a closely held secret, and so Westerners were unable to make their own. Knowledge of silk making gradually spread west after two Persian monks smuggled some silk worm eggs out of China in the 6th century C.E. However, China remained the world’s key producer."