2nd century AD (Vae victis!)

Wars of Christian Expansion
As Christianity continued to rise and dominate the cultural and political structures of the Parthian Empire, Armenia, Galatia, Capadoccia, and Egypt, the nations entered a kind of "Alliance." While it was hardly official, the royal families of each nation were friendly with each other, and worked to spread Christianity across the remainder of the Near East. Galatia and Capadoccia were particularly close, with several royal marriages between them. As the second century dawned, the five Christian states began to become more violent with their attempts to expand Christianity. By 114 AD, these attacks began to evolve into full blown war.

Egypt was the first to officially deploy its army, and the other christian nations quickly followed suite. Capadoccia and Galatia quickly began to focus on the Macedonian free regions of Anatolia. Armenia - which was the least devout nation by far - only invaded a half dozen small states bordering it, leaving the Parthians, and the Egyptians to take care of the rest of the near east. Both of there armies, while out of practice, were far more effective than any resistance the disunited states could put up. Quickly, their armies tore through the area, and after 8 years of fighting, most of the Near East was under the control of Christian rulers. The five initial Christian states also greatly expanded their influence, and saw their power grow dramatically.

Gaulic Disorder
Independent of the Christian wars in the near east, the Gauls had their own troubles around the same time. The trouble started in 124, when a small revolt started in Paris. Normally, a revolt like that would have been crushed quickly, but after around 10 years of peace, the Empire was completely unprepared for it.