The Bai are of China's officially recognized 56 ethnic groups, living predominantly in Yunnan's Dali Bai Autonomous Region.
With a population of around 2 million, predominantly living in Yunnan's Dali Autonomous Prefecture 大理白族自治州, the Bai are one of China's larger 'minzu' 民族, a term that is impossible to accurately translate into English: some will use 'ethnic group', but this term does not capture the official recognition the term 民族 entails, some will use the term 'nationality', but since all Bai people are China's citizens like all other Chinese, this term is also misleading.
In the 1950s, when China's Minzu classification 民族识别 project was underway, a number of names were discussed to officially give to this group. A term discussed was also Minjia 民家, the 'civilian households', based on a self-appellation in common use since the times when the Ming dynasty moved millions of Han soldier-settlers into the region, who were called 军家, the 'military households', but while this term was considered to generic, it would have also been somewhat wrong, as this term was focussed on their distinction to those once living in the soldier-settler camps, which had long been abandoned and merged into the general population. However, in the 1930s the term Minjia seemed more in common use than the modern term Bai.
The origin of the name Bai itself is unclear, in modern Chinese it means 'White', leading anthropologists to the speculation that it reflected a preference for the colour white, as opposed to a preference for the colour black that is attributed to the Yi and Lisu people. An early political entity, the 白子国, formed in about 300 CE, uses this term and in other records the character 白 also makes appearances, sometimes in variant writing forms. But since the Bai people lack a written language, there is no way of knowing how they would have called themselves.
But it would be wrong to assume that the modern Bai are merely a historical continuation of a people that lived in the Erhai region many hundred years ago. Chinese history writing records a number of 'barbarian' people in the western Yunnan region, but there is actually almost nothing known about these people.
The famous Yunnan historian Fang Guoyu 方国瑜 states more prosaically:
The Bai are a people that formed out of the various tribes in the Erhai region during the 7th century.