Although the genre of ‘nasab’ (genealogical literature) was a familiar one to the medieval Muslim historian it appears to have had very fluid boundaries. In this paper I will show how digital approaches can be combined with more traditional forms of text criticism to help us delineate this genre, and in so doing further our understanding of a type of historical writing that has been largely neglected in modern studies of Islamic historiography. In order to carry out this analysis I have compared passages taken from a number of works where they report on the same genealogical connections. It will be shown that the traditional means of doing this (i.e. searching manually through indexes by theme or name) can only ever give us a partial answer because the historians in question were drawing from many unreferenced sources. A more systematic approach is therefore needed and this is provided by text reuse detection methods which can scan for instances of common passages and their variants across an extensive digitised corpus of Arabic literature. The results are twofold. First, the combined methodologies create an extensive database list of examples showing variant ways of transmitting similar historical information and this allows us to consider the distinct contexts of transmission. It will be shown that nasab literature is well-placed to allow us to discuss genre more widely given that its long-term popularity transcended both sectarian and geographic divides; it also helps that the information preserved within it is relatively stable. The second result is that we will be able to compare the digital and traditional methodologies in light of each other. Where the traditional methodology is shown to have shortcomings this has an impact on what we think we know about other types of historical writing that have yet to be systematically searched for text re-use (e.g. chronicles and tabaqat works). Conversely, where the traditional methodology is shown to uncover connections missed by automatic text reuse detection, we will be able to consider ways to improve our digital methods.