We present quantitative evidence that the mita introduced by the Spanish crown in 1573 caused the decimation of the native-born male population. The mass baptisms after the conquest of Peru in 1532 resulted in the assignation of surnames for the first time. We argue that past mortality displacement and mass out-migration were responsible for differences in the surnames observed in mita and non-mita districts today. Using a regression discontinuity and data from the Peruvian Electoral Roll of 2011, we find that mita districts have 47 log points fewer surnames than non-mita districts, and fewer surnames exclusive to one location.