While based on generally similar principles, legal evolution took place locally or at the most regionally, to suit the requirements of any given society. Interaction between these different societies then must have resulted in useful innovations being adopted and adapted for their own respective needs by many societies, and less useful practices being abandoned as a result. It thus is quite likely that both the early medieval Irish and Welsh laws, the two that have survived for posterity in sufficient detail to be reasonable interpretable, are local developments, having originated where they are documented, but constantly subject to outside influence and internal innovation, and thus not particularly dissimilar to other laws practised in their vicinity at the time they were recorded.