Surname distribution could offer substantial information regarding population migration. In this study, based on surname distribution, a novel index for measuring the migration intensity of a single region is proposed – the SRMI (Single-Regional Migration Intensity) – and is applied at the scale of prefectures in China. The prefectures with similar values of SRMI tend to adjoin each other on the administrative map, resulting in several distinct areas. The migration intensity is the highest in the northeastern, followed by the Central Plain and the Yangtze River Basin, and the lowest in the southern China with a larger ethnic minority population. The index of SRMI provides a new approach to study migration intensity in other countries and regions. The empirical results offer a fresh perspective of the historical migration characteristics in China. •SRMI index is an innovative tool measuring historical migration intensity.•Surname-based approach overcomes the challenge of data scarcity.•Application in Chinese prefectures reveals distinct migration patterns.•SRMI index undergoes mutual validation with the established CRSED index.