salt manufacturing industry的意思|示意

History: the history of Zigong is tightly connected with salt industry and the city is well-known for its 1,900 years of salt manufacturing history.

历史：自贡的历史和盐业密不可分。自贡也因其1900年的制盐历史而成为历史名城。

History: the history of Zigong is tightly connected with salt industry and the city is well-known for its 1, 900 years of salt manufacturing history.

历史：自贡的历史和盐业密不可分。自贡也因其1900年的制盐历史而成为历史名城。