I was looking up the history of Vietnamese immigration to the United States (as one does on a cold and wet day, with nothing better to do), and was struck by contrary claims that Vietnamese immigration is relatively recent (mid-20th century) and yet some had come in as "menial laborers" in the 19th century. Which makes me wonder if folks in the US did not strongly distinguish between ethnic Chinese immigrants and immigrants from other parts of Asia, lumping them together as "Chinese" regardless of ethnicity and place of origin. Is this the case, or am I way off base?
I can only speak for The Oregon Territory, and the states of Oregon and Washington, but there are no recorded Vietnamese labors in the 19th Century in any of the hundreds of records of that time period I've personally read. If there were, they were most likely sailors as ship Captains would literally take anyone they could, and in the 1860s on, frequently did so by force or coercion.
But in a lot of people's minds at that time anyone who was from Asia was lumped under the term Chinese, China Man, or other more obviously racist terms. The same way pretty much all Indians were lumped together. The second biggest Asian population on the West Coast were Japanese who were very commonly lumped in with the Chinese in White Settler's mind. Despite the fact that they tended to self-segregate pretty heavily when living and working in the same area.
Oregon had a group of about 600 Sikh laborers who did mostly road work in the Willamette Valley, who were mistakenly called Chinese in newspapers of the time. More than one article talking about them literally noted they were from India too.
At the same time though, Hawaiians were very definitely separated. They tended to be really good sailors and were given a measure of respect because of that - the international shipping trade was literally the life blood of the nation at that time, and there isn't a lot of room for racism in such close quarters.
Japanese and Chinese started being acknowledge as distinct group when the first gold strikes started happening in 1855. Chinese laborers almost immediately went to work at the Gold Mines, while Japanese mostly stayed at the canneries.