The Marcomannic Wars (Latin: bellum Germanicum et Sarmaticum, "German and Sarmatian War") were a series of wars lasting from about 166 until 180 AD. These wars pitted the Roman Empire against, principally, the Germanic Marcomanni and Quadi and the Sarmatian Iazyges; there were related conflicts with several other Germanic, Sarmatian and Gothic peoples along both sides of the whole length of the Roman Empire's northeastern European border, the river Danube. The struggle against the Germans and Sarmatians occupied the major part of the reign of Roman emperor Marcus Aurelius, and it was during his campaigns against them that he started writing his philosophical work Meditations. Background Secure for many years following his ascension to power, the Roman Emperor Antoninus Pius never left Italy; neither did he embark on substantial conquests, all the while allowing his provincial legates to command his legions entirely. Historian Adrian Goldsworthy posits that Pius's reluctance to take aggressive military action throughout his reign may have contributed to Parthian territorial ambitions. The resulting war between Parthia and Rome lasted from 161 to 166 AD (under the joint rule of Marcus Aurelius and Lucius Verus) and, although it ended successfully, its unforeseen consequences for the Empire were great. The returning troops brought with them a plague (the so-called Antonine Plague), which would eventually kill an estimated 7 to 8 million people, severely weakening the Empire. Despite the consequences of the plague, historian Kyle Harper contends that the event should not be treated as a fatal blow to the Empire. Instead, Rome's resilience was demonstrated since the Empire remained intact and Roman birth rates in the decade following the plague subsequently increased. At the same time, in Central Europe during the second-century AD, the first movements of the Great Migrations were occurring, as the Goths began moving south-east from their ancestral lands at the mouth of River Vistula (see Wielbark culture), putting pressure on the Germanic tribes from the north and east. As a result, Germanic tribes and other nomadic peoples launched raids south and west across Rome's northern border, particularly into Gaul and across the Danube. Whether this sudden influx of peoples with which Marcus Aurelius had to contend was the result of climate change or overpopulation remains unknown. Theories exist that the various Germanic tribes along the periphery of the Empire may have conspired to test Roman resolve as part of an attempt to bring to possible