Austrasia (ôstrā´zhə), northeastern portion of the Merovingian kingdom of the Franks in the 6th, 7th, and 8th cent., comprising, in general, parts of E France, W Germany, and the Netherlands, with its capital variously at Metz, Reims, and Soissons. It originated in the partition (511) of the realm of the Frankish king Clovis I among his four sons after his death. Austrasia was constantly troubled by dynastic rivalries between its rulers and those of the neighboring kingdom of Neustria. These struggles, both political and cultural, reached their climax in the fierce fights between Queen Brunhilda of Austrasia and Queen Fredegunde of Neustria. During the reigns of Clotaire I, Clotaire II, and Dagobert I, Austrasia was temporarily reunited with Neustria. This rivalry was only part of the regionalism that eventually brought an end to Merovingian rule. With the decline of the royal power in Austrasia, the office of mayor of the palace developed into the real seat of power and finally became hereditary in the family of the Carolingians. Austrasia became part of the Carolingian empire.