From what I understand, hard delineations for archaeological eras (Bronze Age, Iron Age, Middle Ages) really only applies in specific circumstances. For instance, the Near East transitioned from Bronze Age to Iron Age around 1200 BC, but other cultures didn't even start the Bronze Age until much later, if at all. The Aboriginal Australians or Native Americans were still technically considered "Neolithic" well into the modern era, at least to the late 19th century AD.

But when it comes to the delineation between "Paleolithic" and Neolithic, the division seems to be much more harsh. In a single era, from roughly 12,000-8,000 BC, every single Paleolithic culture on earth seems to have totally disappeared without a remnant, and were entirely replaced with Neolithic culture. In fact, I find history or anthropology textbooks have a tendency to describe the Paleolithic era as a single block, without any differentiation between one part of the world or another.

So my question is this: Is there any Paleolithic culture that lasted long enough to be contemporary with historical records (post 3500 BC), or did they indeed all die out in a single period? What was the last region to hold a remnant of Paleolithic culture before becoming Neolithic? And finally, what caused the transition between these two eras to be so much more straight forward than other Archaeological periods, such as Neolithic cultures that lasted well into the Industrial Age?