Some of the world's oldest known pottery pieces were developed by the Jōmon people in the Upper Paleolithic period, dating back as far as 16,000 years. The name "Jōmon" (縄文 "Jōmon") means "cord-impressed pattern", and comes from the characteristic markings found on the pottery. The Jōmon people were Mesolithic hunter-gatherers, though at least one middle to late Jōmon site (, ca. 1200–1000 BC) had a primitive rice-growing agriculture. They relied primarily on fish for protein. The ethnic roots of the Jōmon period population are heterogeneous and can be traced back partially to the Tibetan Plateau, Siberia and Southeast Asia (Taiwan) respectively.