Why are you being downvoted? This is a completely valid question.
Yes, authentic Chinese food definitely existed in the 19th century in the US and the first Chinese restaurants started popping up in the 1850's (Canton Restaurant opened in 1849) and were serving prospectors during the Gold Rush. The earliest Chinese restaurant still around today opened in 1917 in Butte, Montana and is called Pekin Noodle Parlor. In the 1920's going to 'chow chow houses' was a trendy thing for Californians to do on a night out.
Haiming Liu's book goes into the history of Chinese food in America quite extensively.
Cecilia Chiang didn't do anything that hadn't already been done by other Chinese restaurateurs in decades prior but she did a great job of repackaging it in a nice wrapper. She did for Chinese food what places like Hill Country are trying to do for BBQ.