The study includes anthroponymic and oikonymic data on the Christian population in the western part of Western Thrace (Xanthi region) and in the southern regions of the Central Rhodopes (Smolyan region, Zlatograd region). The material is excerpted from Ottoman tax registers dating from the mid-16th century. The anthroponymy included in them is examined in detail in terms of origin and as a source of information about the life of Christians at that time (employment, status in the local Christian community, etc.). A comparison is made with anthroponymic material from the Rupchos region in the Central Rhodopes and with anthroponymy from the 15th century from different parts of the Bulgarian ethnic territory. This makes it possible to see the specificity of the local anthroponymic system in regional and pan-Bulgarian terms. The trends in its development are shown. The comparison with data from toponymic and anthroponymic studies of Bulgarian settlements in Western Thrace and in the Central and Eastern Rhodopes from more recent times presents a more complete picture of the Bulgarian presence there.