This map; which was drawn in the mid-1930s; shows the outline of the British Settlement (which would become the heart of the International Settlement) in relation to the Chinese City (Nanshi); the Huangpu River and Suzhou Creek; in 1854. International attention to Shanghai grew in the 19th century due to its economic and trade potential near the mouth of the Yangtze River. During the First Opium War (1839-1842); British forces temporarily held the city. The war ended with the 1842 Treaty of Nanjing; opening the treaty ports; Shanghai included; for international trade. The Treaty of the Bogue signed in 1843; and the Sino-American Treaty of Wangsia signed in 1844 together allowed foreign nations to visit and trade on Chinese soil; the start of the foreign concessions. In 1854; the Shanghai Municipal Council was created to manage the foreign settlements. In 1860-1862; during a civil war Shanghai had been invaded twice. In 1863; the British settlement; located to the south of Suzhou creek (Huangpu district); and the American settlement; to the north of Suzhou creek (Hongkou district); joined in order to form the International Settlement.