Answer:
Asians migrated to the United States during the California Gold Rush.
Explanation:
During the California Gold Rush, a very number of people migrated to the West. The reason why such mass migration happened is that people simply wanted to get rich by finding larger amounts of gold. Now while there was gold in California, the exaggerations as to how much there is were very big which fooled a lot of people.
It was not just people that already lived in the United States in the eastern part of it, but people from all over the world heard about the gold in California. Asians, mostly Chinese, flocked to try and migrate to the United States. Many of them managed to do so, but the majority ended up empty-handed and instead of getting rich with gold ended up working on infrastructural projects or mines. Because of the huge amount of Chinese people trying to migrate to the United States, as well as their lower requirements when it came to wages, the United States banned them for several decades and did not allow Chinese people to migrate to the country.