Previous studies of the East African upper mantle have invoked one or more mantle upwellings with varying thermochemical nature to underly the distribution of surface volcanism. For example, Boyce and Cottaar (2021) suggest that a hot, chemically distinct upwelling beneath the southern East African Rift (EAR) is sourced from the African Large Low Velocity Province (LLVP), while magmatism in Ethiopia may lie above an additional purely thermal upwelling. Constraints on chemical heterogeneities in the upper mantle may be derived from studying the seismically observable impedance contrasts that they produce. Away from subduction zones, two causal mechanisms are possible to explain the X-discontinuity (X; 230-350km): the coesite-stishovite phase transition and/or carbonate silicate melting, both of which require entrainment of basalt from the lower mantle. Intriguingly, carbonate silicate melt was invoked by Rooney et al., (2012) to explain the discrepancy in upper mantle temperature anomalies predicted by seismic wavespeed and petrological estimates beneath East Africa. Further, active carbonatite magmatism occurs along the edge of the Tanzanian craton (Muirhead et al., 2020). Several recent regional to continental receiver function (RF) studies have identified potential observations of the X in East Africa. These studies are not focused on the presence of these upper mantle phases or lack the spatial sampling needed to robustly identify the X and its causal mechanism. Targeted high-resolution observations of the X are required to confirm the presence of exotic converted phases in the East African upper mantle and their relationship to mantle upwellings. We capitalise on the new TRAILS dataset from the Turkana depression (Bastow, 2019; Ebinger, 2018) and an adjacent network in neighbouring Uganda (Nyblade, 2017), to supplement our existing RF database and characterise the X across active continental rift setting in unprecedented detail. The prevalence of the X is mapped beneath East Africa, and subsequently compared to other areas of the African continent.