Khawlān and Jumā'ah are two out of eight tribes of the Khawlān b. 'Āmir confederation in Southwest Arabia, the territories of five of them being in Yemen and three in Saudi Arabia. Whereas the Yemeni tribes Munabbih, Sahār and Rāzih are well explored, little is known about the tribal structures of Jumā'ah and the homonymous tribe Khawlān. This article provides an overview of the present-day tribal structures of Khawlān and Jumā'ah, and traces their historical formation through comparison with the respective information available in the historical and geographical works of the Yemeni geographer and historian al-Hasan al-Hamdānī, dating back to the tenth century AD. The results of this study show that Jumā'ah and Khawlān were historically open to processes of social, spatial and genealogical changes. Whereas Jumā'ah can trace its lineage directly back to the ancestor Khawlān b. 'Āmir, Khawlān tribe represents a much looser entity of mutual alliances, which corresponds to its lack of genealogical coherence. Among Khawlān and Jumā'ah, the rhetoric of shared 'ancestry' is thus to a greater or a lesser extent a statement of identity and follows the general Middle Eastern practice in conceptualising groups as kin.