Contemporary Bedouin-related publications about tribal groups reveal a persistent interest in lineages. This article places this phenomenon within the larger framework of Bedouin self-representation and explores the nature and specific uses of the complex and polysemic notion of nasab in treatises and speech. The ambiguity resulting from a tension between the pragmatic context of local articulation and circumstantial (re-)definition and the ideological significance, purportedly unchangeable and defined character and moral value of nasab is reflected in historical and modern discourses as well as in pervasive references to tribal groups as being defined by nasab. The particular concomitance of practical and ideological aspects is the reason for the lasting impact of this notion, as its structure allows for the negotiation of both political issues and individual and collective identities. The publications considered here, mostly from Syria, Jordan, and Iraq, vary between an affirmative stance that often seeks to define prestigious lineages and an attempt to balance the obvious uncertainties of the data with an interest in establishing the identity of tribal groups and narratives referring to descent. As Bedouin lore puts it, the concept of belonging defined by origins in terms of agnatic descent (nasab) is challenged, and sometimes superseded, by the affinity established through locality and cohabitation.