During the california gold rush, about 25,000 laborers migrated to california from

China

Explanation:

Early in 1849 the news of the gold fever was already known all over the world, and a huge amount of gold researchers and dealers began arriving from almost every continent.

Those who came from Asia, especially from China, began to arrive in 1849, initially in small numbers. In Chinese, California was called the "Golden Mountain."

why was the national assembly formed by the third estate?

the estates-general had not been assembled since 1614, and its deputies drew up long lists of grievances and called for sweeping political and social reforms. the third estate, which had the most representatives, declared itself the national assembly and took an oath to force a new constitution on the king.

i would think it's industries and hydroelectric power