 Complete the following phrase:  Qianshan became the seat of the subprefect or keun-min-foo  jūnmínfǔ in 1731. He was charged with dealing with the foreign settlement and overseeing their trade with Guangzhou Canton. As part of these duties, he controlled the permits needed for pilots yǐnshuǐrén of the ships sailing north through the Humen Bocca Tigris or Bogue to the Huangpu Anchorage Whampoa, now Pazhou. He would ensure that foreign ships headed upriver had some cargo apart from silver dollars and bullion. He was also sometimes obliged to quarantine Macaos market, prohibiting Chinese farmers and merchants from trading there and supplying its food, in order to maintain the freedom of the areas Chinese to practice Buddhist and local rituals, which the Portuguese periodically attempted to prohibit. In the lead-up to the 