This paper examines preverbal clitic clusters in the Tanzanian Rift Valley, an area of high linguistic diversity with representatives of the Bantu, Cushitic, and Nilotic families, as well as Sandawe (possibly a distant member of the Khoi-Kwadi family), and the language isolate Hadza. An earlier work (Kießling, Roland, Maarten Mous & Derek Nurse. 2008. The Tanzanian Rift Valley area. In Bernd Heine & Derek Nurse (eds.), A linguistic geography of Africa , 186–227. Cambridge: Cambridge University Press) identified preverbal clitic clusters as a widespread feature across many languages of the Rift Valley, and posited the preverbal clitic cluster as a feature characteristic of a ‘Tanzanian Rift Valley Area’. The current paper provides further detail on preverbal clitic clusters across the languages of the region and examines possible routes of development for these structures. From this analysis, the picture that emerges is complex: contact scenarios cannot be restricted to ones in which West Rift Cushitic or its predecessor languages are the only models for the development of a preverbal clitic cluster and, in the case of Sandawe (and perhaps the Datooga varieties), it appears as if the development of a preverbal clitic cluster cannot be linked to contact at all. In terms of what this means for the ‘areality’ of the Tanzanian Rift Valley, this paper forgoes discussions about geographical delineation or arguments for or against a ‘Tanzanian Rift Valley Area’ in favour of highlighting the individual historical events (c.f. Campbell, Lyle. 2017. Why is it so hard to define a linguistic area? In Raymond Hickey (ed.), The Cambridge handbook of areal linguistics , 19–39. Cambridge: Cambridge University Press) that may have given rise to preverbal clitic clusters in the languages of our sample, as well as encouraging continued investigation into the nature of these histories, both from a linguistic and interdisciplinary perspective.