Sheep, domesticated since the Neolithic period, can easily be herded and tended by shepherds (Herdsman) and sheepdogs (Pastoral economy). They are mobile, extremely adaptable to different climates and terrains, and capable of extensive grazing on poor soil (including moors); they are undemanding livestock with a high reproductive performance. Initially found only in Europe, Asia, and Africa, domestic sheep came to America, Australia, and New Zealand in the course of early modern colonization.