What peoples – neighbors of Byzantium adopted religious teachings other than Orthodoxy?

What peoples – neighbors of Byzantium adopted religious teachings other than Orthodoxy? Are the reasons for this choice similar to the reasons for the spread of world religions around China?

The reasons are the same as in China. The neighbors of Byzantium could receive heretics – Monophysites, Nestorians, Arians. Thus, the Armenians, Egyptians and Ethiopians became Monophysites, some of the Syrians and steppe nomads became Nestorians, and the Goths became Arians.

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