That might be a local thing, Hong Kong being a British colony means there's plenty of people in the UK for whom Asian means Chinese.
The term for East Asian was Oriental which is now considered racist/passé for some obscure reason.
I assume you mean in the US but the 1882 Chinese Exclusion Act makes no mention of race and anti-miscegenation laws speak of Mongolians(presumably to mean people of East Asian ancestry in general).
I think Oriental in the US like the alternative Asiatic applied to all Asians from Istanbul to Vladivostok.