What was the gentlemen's agreement of the late 1800s apex?

The Gentlemen's Agreement was an agreement between the United States and Japan that restricted the immigration of Japanese laborers to America. This agreement was a response to the growing number of Japanese workers in California. Due to their numbers and widespread racism, they often met with hostility. The agreement that was eventually reached between Japan and the United States consisted in Japan agreeing to deny passports to laborers intending to move to the United States and recognizing the right of the United States to exclude Japanese immigrants holding passports originally issued for other countries.

it affected it because the kingdoms (with trade) slowly got richer and richer.