Final answer:
Florence took approximately 200 years to recover its population lost to the plague, achieving this by the 16th century, whereas Sienna took several centuries due to additional challenges. Precise timelines are difficult to ascertain because of incomplete historical demographic records.
Step-by-step explanation:
The recovery time of population levels following the devastation of the plague in cities like Florence and Sienna can be challenging to pinpoint due to a variety of factors, including the lack of precise demographic records from that period. However, it is known that the population of Florence, which was one of the most populous and powerful cities in Europe before the plague, did not regain its former peak until the 16th century, roughly 200 years after the plague hit in 1348. On the other hand, Sienna, which was also severely affected by the plague, experienced a slower recovery due to the additional socio-political and economic challenges it faced, taking several centuries to fully recover.
Several factors affected the rate of population recovery in these areas, including recurring outbreaks of the plague, economic stagnation, and migratory movements. These cities' experiences underscore how the Black Death cast a long shadow over the societal and demographic landscape of medieval Europe.