Answer:
Pleistocene Epoch
Step-by-step explanation:
Modern humans coexisted with woolly mammoths during the Upper Palaeolithic period when the humans entered Europe from Africa between 30,000 and 40,000 years ago. Before this, Neanderthals had coexisted with mammoths during the Middle Palaeolithic, and already used mammoth bones for toolmaking and building materials. Woolly mammoths were very important to ice-age humans, and human survival may have depended on the mammoth in some areas.
The Pennsylvania period, Precambrian period, and the Palezoic Era all existed millions of years before mammoths and humans.