Duchy of Aquitaine
As a duchy , it broke up after the conquest of the independent Aquitanian duchy of Waiofar , going on to become a sub-kingdom within the Carolingian Empire , eventually subsumed in West Francia after the 843 partition of Verdun . 
<triplet> Carolingian Empire <subj> West Francia <obj> replaced by <triplet> West Francia <subj> Carolingian Empire <obj> replaces