Archaeological and genetic evidence indicates that the earliest inhabitants of what is now China migrated from Central Asia (Mongolian steppe, Siberian fringes) during the Paleolithic, ~40,000+ years ago.
Later migrations added diversity: Tibeto-Burman groups (SW), Austroasiatic (S), Turkic/Mongolic (N/NW), Austronesian (coastal/ Taiwan). But the core cultural lineage stems from indigenous Neolithic farmers of the Central Plains.