A ban on exports of silkworms from China was broken when a princess hid the eggs in her hair on her marriage to a Western potentate.
桑蠶技術的輸出，以周初箕子傳入朝鮮（韓國）為最早。而後日漸廣佈，到秦漢時又由朝鮮輸往日本。蠶桑技術傳入中亞，相傳是在西元一世紀初，中國有一位公主外嫁到西域，將蠶種束在發髻，到了關防，官吏不敢檢查公主衣帽，蠶種便被帶入西域。