Note: This talk has not gone through a process of peer review, and findings should therefore be treated as preliminary and subject to change. How to cite: Mous, Maarten. 2021. Towards the linguistic history of Rangi and Mbugwe. Talk Given at Rift Valley Webinar Series 27/01/2021. DOI: https://doi.org/10.5281/zenodo.4498156 Abstract: This seminar is actually the beginning of my research into this topic and will present questions, considerations, and ideas of what to look into. I need to understand more about the linguistic history of these two languages in order to form a view on the linguistic history of the Tanzanian Rift valley as a contact zone. My assumption is that Rangi and Mbugwe are closely related and form one genetic unit but the main research question is whether they are part of a genetic subgroup F30; are they genetically related to Nyaturu, Nyilamba and Ihanzu or is the resemblance through contact? And there is a need to explain the properties that Rangi and Mbugwe share with Pare and Chasu (Masele & Nurse 2003). I do not expect to answer this question but to lay out the problem and sketch how to go about it. In addition to these fundamental questions, I need to know more of all the various language contact phenomena with the languages in the area and across different periods of time, and an inventory of specific research questions to achieve this.