This paper explores the relationship between naming practices, race, and tribal origins in Saudi Arabia. In so doing, it sheds light on a highly significant though little studied phenomenon in the kingdom, Saudi Arabia’s modern genealogical culture. One manifestation of this culture is the effort by Saudis of sedentary origin to affirm their attachment to prominent Arabian tribes, a process documented in thousands of books and articles over the past four decades. This process of genealogical affirmation has played out against a bleak historiographical landscape, where textual evidence for most assertions is scarce, and oral narrations have been devalued in the modern age. Drawing on interviews, manuscripts, family documents (both authentic and falsified), and ethnographic fieldwork conducted between 2011 and 2012 in the northwest Arabian oasis town of al-'Ula, I plot the efforts by a Saudi micro-community to assert its connections to a prominent Arabian tribe, Harb. I show how the historical inhabitants of al-'Ula, the 'Alawna, have had to deal with a legacy of skepticism concerning their origins, one rooted in perceived racial or ethnic difference and the often unacknowledged stigma of slave origination that blots their historical reputation by Arabian tribal standards. This skepticism is compounded by the fact that al-'Ula is geographically peripheral to the dominant region of the kingdom, Najd (central Arabia), where narratives of lineal exclusivity have become measures of authentic national belonging. For those inhabitants of al-'Ula concerned with legitimating their genealogical position in the kingdom, I conclude, ridding themselves of the toponymic 'Alawna label and replacing it with a tribal nisba (i.e. al-Harbi) was the first step in establishing a basis of commonality with the kingdom’s dominant status group, Saudis of prominent tribal origin. In presenting the case of the 'Alawna, I hope to demonstrate the fluid and dynamic nature of tribal identification and affiliation in the modern kingdom, as well as the intimacy and centrality of tribal identification to the modern Saudi condition.