Complex sentence: After the death of Attila, the Hunnic empire disintegrated in days, and the previously subjected Gepids formed a new kingdom in the area, only to be defeated 100 years later by the Avars.
Split into simpler sentences: After the death of Attila, the Hunnic empire disintegrated in days. The previously subjected Gepids formed a new kingdom in the area, only to be defeated 100 years later by the Avars.