For most Chinese immigrants of the 1850s, San Francisco was only a transit station on the way to the gold fields in the Sierra Nevada. According to estimates, there were in the late 1850s 15,000 Chinese mine workers in the "Gold Mountains" or "Mountains of Gold" (Cantonese: "Gam Saan", 金山). Because anarchic conditions prevailed in the gold fields, the robbery by European miners of Chinese mining area permits were barely pursued or prosecuted and the Chinese gold seekers themselves were often victim to violent assaults. At that time,"Chinese immigrants were stereotyped as degraded, exotic, dangerous, and perpetual foreigners who could not assimilate into civilized western culture, regardless of citizenship or duration of residency in the USA". In response to this hostile situation these Chinese miners developed a basic approach that differed from the white European gold miners. While the Europeans mostly worked as individuals or in small groups, the Chinese formed large teams, which protected them from attacks and, because of good organization, often gave them a higher yield. To protect themselves even further against attacks, they preferred to work areas that other gold seekers regarded as unproductive and had given up on. Because much of the gold fields were exhaustingly gone over until the beginning of the 20th century, many of the Chinese remained far longer than the European miners. In 1870, one-third of the men in the Californian gold fields were Chinese.