Silk was used by the state both as a means of payment, and of diplomacy. Raw silk was bought from China and made up into fine brocades and cloth-of-gold that commanded high prices through the world. Later, silk worms were smuggled into the empire and the overland silk trade became less important. After Justinian I the manufacturing and sale of silk had become an imperial monopoly, only processed in imperial factories, and sold to authorized buyers. The raw silk merchants could buy the raw silk from outside Constantinople but did not themselves have the authority to travel outside the city to get it — possibly in order not to jeopardize the activities of the provincial merchants selling the silk.