It is relatively new actually. I mean the ideas, maybe not since Jefferson had similar ideas hundreds of years ago but the cooption of the words anarchism and libertarianism, both of which were historically leftist movements, was popularized by Murray Rothbard in the 1970s. He was also pro-segregation, just to demonstrate what kind of people we’re discussing here.

Rothbard agreed privately that his movement was fundamentally not anarchism but for whatever reason in his public writings, he claimed otherwise. I suspect it was just to troll leftists but who knows.