The Neolithic is defined by the domestication of plants and animals, the introduction of pottery and polished stone axes, and the construction of the first houses and monuments. Much forest clearance took place and great structures of stone and earth served as places of burial and the focus for the spiritual lives of societies. Although life became more settled it is thought that elements of the wandering way of life may have persisted for some time. Flint tools are the most commonly found artefacts dating to this time.