The "Barons of Wales" refers to the noble landowners who held significant power and influence in medieval Wales. These barons were often granted lands by the English crown, particularly after the conquest of Wales in the late 13th century. They played a crucial role in the governance and administration of their territories, managing local affairs and maintaining order. Many of these barons were part of the Marcher Lords, who governed the border regions between England and Wales. They were responsible for building castles, such as Caernarfon Castle and Harlech Castle, to assert control and defend against potential uprisings from the Welsh population.