The California Gold Rush happened between 1848 and 1855, this was where many people went to California, as gold was found there. This was a chance to earn money and become rich, so a lot of people took that chance.
The people who would go to California in hopes of finding gold during the gold rush were called forty-niners. They were named this because many of them arrived in the year 1949, a lot of them even coming from other countries and leaving their families, in hopes of finding gold.