History: Old China

Demography
Hundreds of ethnic groups have existed in China throughout its history. The largest ethnic group in China by far is the Han. This group, however, is internally diverse and can be further divided into smaller ethnic groups that share similar traits.
Over the last three millennia, many previously distinct ethnic groups in China have been Sinicized into a Han identity, which over time dramatically expanded the size of the Han population. However, these assimilations were usually incomplete, and vestiges of indigenous language and culture still often remain in various regions of China. Because of this, many within the Han identity have maintained distinct linguistic and cultural traditions while still identifying as Han.