Recently? The One Drop Rule is recent?
Categorizing anybody who is not British or Germanic as black goes back centuries, as exhibited to throughout the British colonies in the world. They called Indians in India - who are the true Aryans, btw - Black. To this day in Australia, Aboriginals are called Black, as in African, despite being Caucasoids. Even Southern Europeans are considered not white and thus not true Europeans by them, despite them being the original Europe for millenia before the Romans discovered the British Isles and the Germanic tribes.