Chinese traders went to distant lands on foot, horseback etc. They carried silk with them. These paths came to be known as silk route.
(1) Sometimes, Chinese rulers sent gifts of silk to rulers in Iran and west Asia. From there, knowledge of silk spread further west.
(2) It was very costly, as it had to be brought all the way from China. People living along the route often demanded payments for allowing traders to pass through.
(3) Some rules tried to control large portions of the route. They demanded taxes, tributes and gifts from the traders. In return, they generally protected the traders from attacks by robbers.
(4) In history the best known of the rulers who controlled the Silk Route were the Kushanas. During their rule, a branch of the Silk Route extended from central Asia down to the Indus valley. Silk was shipped westwards to the Roman empire from here.