<P> The Act controlled "undesirable" immigration by establishing quotas, and barring immigrants of some specific national origins . The nationalities barred were in the "Asia--Pacific Triangle", which included the Middle East, the Asiatic Soviet Union (Georgia, Azerbaijan and Central Asia), Japan, China, the Philippines (then under U.S. control), Siam (Thailand), French Indochina (Laos, Vietnam, and Cambodia), Singapore (then a British colony), Korea, the Dutch East Indies (Indonesia), Burma (Myanmar), British India, Ceylon (Sri Lanka), and Malaya (mainland part of Malaysia). Following the Naturalization Act of 1790 and Naturalization Act of 1870, the 1924 Act declared that only people of white or African descent were eligible for naturalization, and the Act forbade further immigration of any persons ineligible to be naturalized . The Act set no limits on immigration from Latin American countries . </P> <P> In 1901 - 1914, 2.9 million Italians immigrated, an average of 210,000 per year . Under the 1924 quota, 4,000 per year were allowed . By contrast, the annual quota for Germany after the passage of the Act was over 57,000 . Some 86% of the 155,000 permitted to enter under the Act were from Northern European countries, with Germany, Britain, and Ireland having the highest quotas . The new quotas for immigration from Southern and Eastern Europe, and the bar on the "Asia - Pacific Triangle", were so restrictive that in 1924 more Italians, Czechs, Yugoslavs, Greeks, Lithuanians, Hungarians, Portuguese, Romanians, Spaniards, Polish and Russian Jews, Chinese, and Japanese left the United States than arrived as immigrants . </P> <P> The quotas were eased in the Immigration and Nationality Act of 1952 and replaced in the Immigration and Nationality Act of 1965 . </P>

Why did these changes in immigration occur between 1921 and 1925