Japanese prehistoric art is a wide-ranging category, spanning the Jōmon (c. 10,000 BCE - 350 BCE) and Yayoi periods (c. 350 BCE-250 CE), and the entire Japanese archipelago, including Hokkaidō in the north, and the Ryukyu Islands in the south which were politically not part of Japan until the late 19th century. Much about these two periods remains unknown, and debates continue among scholars regarding the nature of the cultures and societies of the period, their number and the extent to which they can be considered to be united, uniform cultures across the archipelago, and across time.