Which group of immigrants was cut off by the gentleman's agreement of the 1800s?

The Gentlemen's Agreement of 1907 affected the Japanese immigrants. Many of these immigrants came to the United States (namely California) under the treaty in 1894, which assured them free Immigration. But tensions started to rise in California, as Japanese children were segregated to separate schools, and in the Gentlemen's agreement, Japan agreed not to issue passports to Japanese citizens entering the United States, while the U.S. agreed to accept the presence of those already immigrated as well as the children in California schools.