 Complete the following phrase:  Shamian Island was an important port for Guangzhous foreign trade from the Song to the Qing dynasty. From the 18th to the mid 19th century, the foreigners lived and did business in a row of houses known as the Thirteen Factories, on the banks of the Pearl River to the east the present Shamian, which was then an anchorage for thousands of boat people. In 1859, Great Britain and France dug an artificial river now called Shajichong to the north, making it an island. Since then, Shamian became a strategic point for city defense during the 