Following the Second Opium War, the Qing Empire was obliged to open more treaty ports by the unequal 1858 Treaty of Tianjin, including Tengchow (now Penglai). Its port being found inadequate, Zhifu—about away—was selected to act as the seat of the area's foreign commerce. The mooring was at considerable distance from shore, necessitating more time and expense in loading and unloading, but the harbor was deep and expansive and business grew rapidly. The harbor opened in May 1861, with its status as an international port affirmed on 22 August. The official decree was accompanied by the construction of the Donghai Customs House (). It quickly became the residence of a circuit intendant ("taotai"), customs house, and a considerable foreign settlement located between the old native town and the harbor. Britain and sixteen other nations established consulates in the town. The town was initially expanded with well-laid streets and well-built stone houses, even for the poorer classes, a Catholic and a Protestant church were erected, and a large hotel did business with foreigners who employed the town as a summer resort.