The isotope–geochronological and geochemical data on the age and composition of rocks of the Butugol Block, located in the eastern part of the Tuva–Mongolian microcontinent of the Central Asian Orogenic Belt, have been obtained. It has been established that the protolith for gneisses is, in one case, volcanic rocks with an age of 1009 ± 8 Ma, and in the other case, potassium meta-sedimentary rocks accumulated in continental marginal basins. The protolith of metavolcanogenic rocks of this complex were formed at the turn of the Mesoproterozoic and Neoproterozoic on the already formed crust, while the metasedimentary rocks were formed owing to the Mesoproterozoic, more rarely Paleoproterozoic and Archean, continental provenances. It has been established that the development of the Butugol metamorphic complex (Butugol Block) differs from the development of other blocks of the Earth’s crust included in the composite Tuva–Mongolian microcontinent.