Complex sentence: After the fall of the Western Roman Empire, the region was pillaged by the Goths, the Eastern Roman Empire, and Avars, annexed to the Lombards Kingdom in 751, and annexed to the Frankish kingdom by Pippin III in 789.
Split into simpler sentences: After the fall of the Western Roman Empire, the region was pillaged by the Goths, the Eastern Roman Empire, and the Avars. It was subsequently annexed to the Lombard Kingdom in 751, and then annexed to the Frankish kingdom by Pippin III in 789.