may be indicative of diverse peoples who possibly belonged to a common culture, known as the Jomon. ... These results suggest a level of inter-regional heterogeneity not expected among Jomon groups. This observation is further substantiated by the studies of Kanzawa-Kiriyama et al. (2013) and Adachi et al. (2013). Kanzawa-Kiriyama et al. (2013) analysed craniometrics and extracted aDNA from museum samples that came from the Sanganji shell mound site in Fukushima Prefecture dated to the Final Jomon Period. They tested for regional differences and found the Tokoku Jomon (northern Honshu) were more similar to Hokkaido Jomon than to geographically adjacent Kanto Jomon (central Honshu). Adachi et al. (2013) described the craniometrics and aDNA sequence from a Jomon individual from Nagano (Yugora cave site) dated to the middle of the initial Jomon Period (7920–7795 cal BP). This individual carried ancestry, which is widely distributed among modern East Asians (Nohira et al. 2010; Umetsu et al. 2005) and resembled modern East Asian comparison samples rather than the geographical close Urawa Jomon sample." A study published in the scientific journal Nature by Jinam et al. in 2015, using genome-wide SNP data comparison, found that the Hokkaido Jōmon samples, ancestral to the Ainu people, carried two gene alleles associated with facial features that are commonly found among Europeans and Middle-Easterners. Kondo et al. 2017, analyzed the regional morphological and craniometric characteristics of the Jōmon period population of Japan, and found that they were morphologically heterogeneous and displayed differences along a Northeast to Southwest cline. They concluded that the "Jomon skulls, especially in the neurocranium, exhibit a discernible level of northeast-to-southwest geographical cline across the Japanese archipelago, placing the Hokkaido and Okinawa samples at both extreme ends. The following scenarios can be hypothesized with caution: (a) the formation of Jomon population seemed to proceed in eastern or central Japan, not western Japan (Okinawa or Kyushu regions); (b) the Kyushu Jomon could have a small-sized and isolated population history; and (c) the population history of Hokkaido Jomon could have been deeply rooted and/or affected by long-term extrinsic gene flows." In 2021, it was confirmed that the ancient population of Hokkaido formed from proper Jōmon people and from "Terminal Upper-Paleolithic people" (TUP people) indigenous to Paleolithic Northern Eurasia. The proper Jōmon groups arrived at about 15,000 BCE from East Asia, and merged with the earlier arrived "Terminal Upper-Paleolithic North Eurasians", to form the local Hokkaido Jōmon. Previously,