I think it will be helpful to analyze the remains of Hongshan and Xiajiadian culture and ancient culture of area between Hebei and Liaoning provinces.
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They also need ancient neolithic and bronze age sample of (1) Erlitou, Longshan, Yangshuo from Central Plains; (2) Majiayao and Qijia from Northwest ?Yellow River; (3) Pengtoushan, Daxi and Qujialing From Yangtze River; (4) ancient 挹婁, 愼 愼, 勿吉Tungusic; and (4) 河姆渡, 浜家浜, and 良渚 from Yangtze Delta 長江江三角. etc. etc.
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Perhaps change reference populations from modern ?samples to ancient neolithic samples in future?