Ash'ār al-Hudhaliyyīn, the anthology of the Hudhayl tribe’s poetry, which dates to around 550-700 CE, is the only complete collection of tribal Arabic poetry from the medieval period. Hudhayl lived near Mecca, and their increased poetic production in the mid-sixth century coincided with the rise of Quraysh, the Prophet Muhammad’s tribe, in Mecca. Although the poetic culture of pre-Islamic Arabia is usually taken to be uniform across the Arabian Peninsula, this study argues that Hudhayl constructed a distinctive social identity in their 4,600-line corpus of poetry. Drawing on non-Arabic sources, including inscriptional sources, this dissertation narrates the emergence of a warrior elite in Najd (central and northeastern Arabia) in the early sixth century, whose poetic culture emphasized equestrianism, hierarchy and connections with sedentary societies such as Sasanian Iran and Byzantium. This group of poets became aesthetically normative and canonical for medieval Arabic philologists. In the late sixth century, however, the tribes of the Hijāz, especially Hudhayl, adapted the stylistic devices of Najd to their own ecological, cultural and ideological world. For example, Hudhayl and other Hijāzī tribes followed different migratory patterns than the Najdī tribes; their pre-Islamic poets are the first to depict the pilgrimage to Mecca as a site for romantic trysts; and they developed innovative forms of elegy. This study draws on modern ethnographies and contemporary anthropological theory to map out Hudhayl’s phenomenological geography, as well as their tribal ideology. Further, through careful philological examination of their tribal and regional intertextualities, it argues that Hudhayl, in distinguishing themselves culturally from other regions such as Najd, Yemen, or Syria, constructs a Hijāzī identity that is self-consciously peripheral but also competitive and assertive. Such a regional culture also elucidates the emergence of Islam.