"Gold Mountain is a commonly used nickname for San Francisco, California, and historically used broadly by Chinese to refer to western regions of North America, including British Columbia, Canada. After gold was found in the Sierra Nevada in 1848, thousands of Chinese from Toisan in Guangdong, began to travel to the West in search of gold and riches during the California Gold Rush.
Chinese people historically referred to California and British Columbia as Gold Mountain, as evidenced by maps and returned Overseas Chinese. However, because gold was also discovered in Australia (Melbourne was referred to as "New Gold Mountain" (新金山), California was more exclusively known as Old Gold Mountain; although "Old Gold Mountain" now specifically refers to San Francisco."
Wikipedia link – https://en.wikipedia.org/wiki/Gold_Mountain_(toponym)