also saying "etc." felt wrong, just didn't quite know how else to put it.
PART I
This is a great example of the often misunderstood phrase "race is a social construct". Often people hear that and think it means "race doesn't exist in any way at all", but what it really means is that the idea of race, how it is defined, and how people are categorized based on that definition is heavily dependent on the historic and institutional particulars of the society they live in. That is to say, one country does not define racial categories the exact same way as another country, even if they are using the same terms.
Of course how this relates to the idea of "Asian" is huge, as any term relating to the largest continent with the largest population would be. The British definition of "Asian" is slightly different than the definition in the United states. The UK Cabinet Office Racial Disparity Unit has a list of "ethnic units" that are racial categories (they seem to use race and ethnicity more fluidly than is done in the United States, more on that in a minute). Note that they state these are options provided for self reporting. The "Asian" category notably includes subcategories of Indian, Pakistani, Bangladeshi, Chinese, and "Any other Asian background", so just in terms of how they are counting Asian, they are mostly looking at people of South Asian descent (which makes sense, those are the biggest communities with Asian origins in the country). Interestingly, "Arab" is considered "Other", ie not white, black, Asian or mixed.
But anyway, this is a long way around of saying that what's really under examination is how "Asian" came to be associated in the United States with basically "Northeast Asia". The long and short is that the first major waves of immigration from Asia to the United States specifically came from China and Japan to the US West Coast, with the resulting racial tensions between these communities and the dominant white population.
Chinese immigration to California had begun during the Gold Rush, and was spurred by a bad harvest in 1852 (causing some 20,000 to immigrate to California). Chinese labor was of course famously used in building railways in California, and in the 1870s immigration increased - some 22,000 immigrated in 1876 and another 10,000 in 1879. By 1880 there were some 105,000 Chinese in the American West, largely from Guangdong Province (a lot of what is commonly considered "Chinese" in the United States is more specifically Cantonese or related to China's southern provinces), and overwhelmingly male. Something like 25 percent of the workforce in California was Chinese. They were notably concentrated in specific professions, like shoe making, cigar making and operating laundries (a Chinese laundry was a very pervasive stereotype into the 20th century), and often worked for lower wages than white workers.
This almost immediately led to local attempts to restrict Chinese immigration: in 1875 the Page Law was passed, which was a federal version of an overturned California state law banning the immigration of Chinese women "sold into slavery", which sounds noble, but was effectively meant to keep Chinese workers from establishing families in the United States through any sort of arranged marriages. Chinese immigrants were viewed as "coolies", namely some sort of semi-savage, not-quite-free laborer who threatened to undermine white male workers. Ironically given contemporaneous theories about whites being superior to and eventually displacing blacks, Indians and "Mexicans", Chinese were considered an "inferior race" that could somehow displace whites unless stopped harshly. Sinophobia became a motivating factor in California politics, with the Irish immigrant Denis Kearney building the Workingmen's Party in San Francisco on the slogan of "The Chinese must go." The party's strength and popularity led to influences on the new state consitution that was written in 1878, noting that "no native of China, no idiot, insane person, or person convicted of any infamous crime" was allowed to vote in the state, and that no "Chinese or Mongolian" could be employed in public works, except as punishment for a crime. I note this because it's worth seeing that the terminology was reaching towards something that would now probably use the term "Asian", while not quite getting there, as white Californians were addressing a specific Asian group in their midst. A state referendum overwhelmingly supported exclusion of all Chinese immigration, and this ultimately led to the Chinese Exclusion Act of 1882 (although some exceptions still existed, notably for Chinese students to come study at US universities).
Ironically, the exclusion of further Chinese immigrants was a spur for Japanese immigration (many coming from Hawai'i) to the US West Coast, and naturally white fears now turned to include this new group. This heightened especially after Japan's defeat of Russia in 1905, leading to fears of "Orientalization of the Pacific Coast" and to the San Francisco School Board segregating its school system, placing Chinese, Japanese and Korean children in separate schools from whites. The Japanese government actually protested the segregation and turned the matter into an international incident, leading to the "Gentleman's Agreement" of 1907, where the United States would not restrict Japanese immigration (in name at least, although Congress passed laws banning immigration from Hawaii, Mexico and Canada in an attempt to restrict Japanese immigration via these locations), but Japan would restrict its emigration flow. Japanese immigration actually increased briefly after the agreement, leading to riots and fear of the "yellow peril" (note that now we are getting more into more general racial terms), before the Japanese government clamped down. The concept of a more generalized "race" can be best seen in this period by the renaming of the Japanese and Korean Exclusion League to the Asiatic Exclusion League - the issue was increasingly less one of specific nationalities and a perceived race coming from East Asia.
So what about other parts of Asia that the United States interacted with at the time, notably the Philippines? To put it bluntly, Americans did not consider Filipinos to be quite the same race as the Japanese, Chinese, Koreans, or "Mongolians". They were too dark, too tropical, and if the former were semi-savage, the latter were even less capable of self rule or of civilization (never mind that they had been Catholic for some two and a half centuries and had declared their own republic in 1898). In this regard, Americans were mostly following the racial theories underpinning colonialism in the 1890s. The first civil colonial governor of the Philippines, William Howard Taft, would speak condescendingly of Filipinos as "little brown brothers", but the US troops busy fighting the insurrection in the country at the time more often referred to Filipinos as "niggers", "dusky fellows", "black devils", or "goo-goos"(which seems to be the origin of "gook"). Theodore Roosevelt would describe Filipinos as living in the "black chaos of savagery and barbarism". The Philippines, like the rest of Southeast Asia, was considered something different from China or Japan.