Chlothar II
Chlothar II defeated Brunhilda and her grandson, reunifying the kingdom. However, in 623, to appease the local nobility and also secure the borders, he gave the Austrasians his young son as their own king. His son and successor, Dagobert I, emulated this move by appointing a sub-king for Aquitaine, with a seat at Toulouse, in 629 and Austrasia in 634.