Pangaea is a supercontinent that existed during the late Paleozoic and early Mesozoic eras, about 300 to 175 million years ago. It was a result of the gradual movement and collision of several smaller continents, eventually forming a single landmass. Pangaea is believed to have been surrounded by a vast ocean called Panthalassa. Over time, Pangaea began to break apart due to tectonic plate movements, leading to the formation of the modern continents we see today.