The density of the black rat population and their plague-bearing fleas determined the spread of the plague. In Ireland it hit first, and hardest, in the Anglo-Norman ports of the south and east, then devastating their close-settled hinterlands. Gaelic Ireland was not immune, but its relative poverty and sparse settlement mitigated its impact and reduced the death toll. The result was an increasing retrenchment of Anglo-Norman control behind the Pale hinterland of Dublin, and a corresponding Gaelic resurgence, both in political power and culture. Professional hereditary castes of poets, physicians, historians and practitioners of traditional Brehon law attended the major Irish chieftaincies. The satire of their bards was reputedly so biting it would cause boils to erupt on the faces of its victims. The resurgence was also abetted by pro-native recruitment policies amongst the clergy, Franciscan and Dominican orders, which was further asserted by the founding of new religious houses in the Gaelic west.