 Human activity has been verified in the Three Gorges area as far back as 27,000 years ago, and by the 5th millennium BC, the lower Yangtze was a major population center occupied by the Hemudu and Majiabang cultures, both among the earliest cultivators of rice.By the 3rd millennium  BC, the successor Liangzhu culture showed evidence of influence from the Longshan peoples of the North China Plain.A study of Liangzhu remains found a high prevalence of haplogroup O1, linking it to Austronesian and Daic populations; the same study found the rare haplogroup O3d at a Daxi site on the central Yangtze, indicates possible connection with the Hmong, although "only small traces" of haplogroup O3d remains in Hmong today.