Changes

The immediate consequences of the plague is it severely limited Byzantine expansion across southern Europe, ending Justinian's dream of reuniting the Roman Empire. It also strained the empire's resources as it had to face renewed threats from the Sasanian Empire, all the while Justinian insisted in financing major building projects and imposing taxes on his devastated population. While the Byzantine Empire ultimately recovered, they did come close to completely collapsing to the Sasanian Empire by the late 6th century and early 7th century. In fact, the Byzantine Empire never recovered to the same level again, which suggests the events of the plague may have contributed to the long-term decline despite short-term recovery of the empire. In northern Europe, the plague likely spread to the British Isles and Scandinavia. Initially these regions were isolated and relatively protected from the plague's spread, but slowly it had spread across the region probably by the 540s CE. Northern Europe would not recover until about the 9th century in terms of its population. Diminished trade and contacts would persist between the wealthier parts of southern Europe and northern Europe perhaps for a century or more, which may have also limited the re-urbanization of parts of Europe after the Roman collapse. The main long-term devastation was the economic consequences of the plague. Diminished labor as well as lost tax revenues meant that the Byzantines could no longer finance major offensives or construction projects as they had prior to the plague. The Sasanians likely saw this as an opportunity to expand into Byzantine territory, which did initially succeed. Many of these lands, particularly Jerusalem, Egypt, and Antioch, were critical to the Byzantines. Thus, the Byzantines launched a series of wars to recover these areas. This depleted both empires, leading to their weakened states. With these two great empires that effectively controlled the most important cities west of India weakened, the situation did enable the rising Arabs in the mid-7th century to take advantage of the situation. At this point, both those great empires were a shadow of their earlier versions.