For the people of the ancient Mediterranean and beyond, the city of Rome had been a symbol of power for centuries, and entering the early 5th century CE, the Eternal City hadn’t been taken by an enemy force since the Gauls had done it about 800 years earlier, an unheard of period of tranquility in a world wracked with almost constant warfare.

Thus, when the Visigoths, whom the Romans considered uncultured and inferior, took the city of Rome and sacked it in 410, the world was stunned. It made theologians of the newly Christianized empire question God’s plan on Earth, and it encouraged many leading Romans to look east to Constantinople for their future. Indeed, the Western Roman Empire would completely collapse in the late 5th century, less than 70 years after the Visigoths sacked Rome, and just how it went from being a superpower to a poorly led, weak, and vulnerable shadow of its former self has preoccupied historians for centuries.

To this day, it remains difficult to trace just when the decline began, but it’s fair to say that the sack of Rome was the result of a number of factors that had been coalescing for many years. In the end, the fall of the Roman Empire was not a tale of cataclysmic events that shattered the sprawling power, but the culmination of centuries of internal dissent and decay, combined with growing external threats that led to gradual decline and eventually to the empire’s final destruction.

In terms of geopolitics, perhaps the most seminal event of the Middle Ages was the successful Ottoman siege of Constantinople in 1453. The city had been an imperial capital as far back as the 4th century, when Constantine the Great shifted the power center of the Roman Empire there, effectively establishing two almost equally powerful halves of antiquity’s greatest empire. Constantinople would continue to serve as the capital of the Byzantine Empire even after the Western half of the Roman Empire collapsed.