The fall of the Roman Empire in 476 AD led to the Dark Ages in Europe. This was due to invasions by barbarian tribes like the Huns, Vikings, and Vandals. Two influential emperors, Diocletian and Constantine, tried to strengthen the empire but it continued to decline. Figures like Charles Martel, Pepin the Short, and Charlemagne helped unite France and establish the Holy Roman Empire, bringing stability to Europe. Charlemagne's empire marked the end of the Dark Ages.