Datasets such as Seshat have allowed researchers to quantitatively test hypotheses about premodern societies and states with great success. Nevertheless, one has to take into account potential sources of bias in the data such as a survivorship bias favouring the inclusion of long-lived over short-lived states. Bayesian methods can be used to complement standard modelling procedures to take this issue into account as is demonstrated by analysing the longevity distribution of premodern states.