Are you a native English speaker? I am. "1800s" means the entire century, not jus the first decade. I'm starting to suspect you're not a native English speaker, but you're posing as one, which makes you probably some sort of sock puppet propaganda machine. "A phrase like the 19th century is often misunderstood because it actually refers to the 100 years preceding the year 1900, that is, the period from 1800 to 1899. The same period can also be described as the 1800s." https://proofreading.org/blog/writing-about-centuries-and-decades-in-academic-writing