China's chief contribution to world clothing has been the development of silk thread and cloth. By 3000 BC the Chinese had domesticated silkworms, feeding them mulberry leaves and unwinding their fresh cocoons to produce long strands of silk fiber. This fiber was spun into thread, and the thread was woven into cloth. By 1500 BC elaborate weaving techniques had been developed, using thread dyed in many colors. Silk is lustrous, soft, and lightweight but warm, and it can easily be dyed. Silk cloth excavated from tombs dating from the 2nd century BC includes gauze (thin, loosely woven fabric), twill (fabric with a woven design of parallel diagonal ribs), damask (fabric woven with patterns on both sides), brocade (heavy fabric woven with an intricate raised design), and plain cloth embroidered with different stitches. Farm women in China of the period were expected to raise silkworms and produce silk as part of their regular household duties.
Silk was used in China, and it was also exported along the Silk Road; this ancient trade route linking China and the Roman Empire was named after the primary export carried on it. The silk trade, conducted between western Asia and the Mediterranean as early as AD 200, brought great wealth to ancient China and sustained the economies of towns along the route. China kept the technology of silk production secret; the ancient Greeks speculated that silk grew on a special tree in China. Christian monks finally broke China's monopoly on silk production in the 400s, when they smuggled silkworm eggs to Syria on their return from China.