A territory sited partially in the Netherlands (province of North Brabant) and partially in Belgium (Brabant and Antwerp), they were divided when Belgium became independent in 1830.
Wace says it was conquered by Arthur during his campaign against Gaul. Wolfram makes Lambekin the Duke of Brabant in Uther's time. It was in this realm Princess Elsam of Brabant (Elsa), perhaps related to Lambekin, was besieged by Frederick de Telramund and subsequently rescued by Lohengrin, Perceval's son, whom she married.
Holland | The Legend of King Arthur