In China, the Yellow River flooded, displacing many peasants, and caused wide spread discontent.  The Taoist sect, Taipang, offered help to the discontented and used the situation to begin a massive peasant rebellion against the Han emperor of China.  The rebellion spread over much of China. In south China, the leader of the Taoist sect, the Way of Five Pecks of Rice, established his own state and army.  The Han emperor was unable to subdue this newly established state.  In Rome, the Praetorian Guards murdered Emperor Pertinax and sold the crown to Julianus.  This precipitated a civil war amongst the strongest Roman generals.  Eventually Septimus Severus gained control of Rome and the Senate.  During the civil war, Parthia took the opportunity to invade Armenia.  After Severus became emperor, he began campaigning in Parthia.

Notable Battles
Cyzicus between Severus and Niger.
Nicaea between Severus and Niger.
Issus between Severus and Niger.