This paper presents an overview of the distribution of reflexive-reciprocal syncretism in Eastern Bantu languages spoken in Tanzania. Most Bantu languages encode reflexive and reciprocal constructions by means of two distinct verbal affixes. However, the Tanzanian Eastern Bantu languages under study have developed reflexive-reciprocal syncretism, in which the originally reflexive prefix has developed into a polyfunctional morpheme coding both reflexive and reciprocal constructions, to the detriment of the original reciprocal suffix. In a sample of 79 languages, reflexive-reciprocal syncretism is attested in 27 neighboring languages, thus constituting a clear areal feature. We propose that reflexive-reciprocal syncretism is not a language-internal innovation but was rather adopted from neighboring non-Bantu languages and subsequently spread out to its current distribution. We locate the heart of this contact-induced spread in the Tanzanian Rift Valley, a convergence zone in north-central Tanzania where languages from multiple African language families are spoken and have been in contact for an extensive period.