The history of Egypt between 1552 and 664 BC, as for earlier periods, is conventionally divided up into usually sequential, numbered dynasties. These are derived from later Epitomes of Manetho's history of Egypt and usually do in fact coincide with real breaks, alterations or divisions in the line of dynastic succession. Several major factors contributed to the shaping, sustaining, and social pervasiveness of the Egyptian world-view. Tradition was an extremely important one. The governmental system enjoyed great authority because of its antiquity and supernatural implications. It was adequate to meet the perennial social and economic needs of the population and it was adept at reinforcing and enhancing its own political power. The period between 1552 and 664 BC is conventionally divided into two main phases, the New Kingdom and the Third Intermediate Period. New Kingdom and later relations with Libya, the other main African contact area, are one of the most intriguing and least studied aspects of Egyptian foreign relations.