We now come to a period, _i.e._, that of the =XIIIth, XIVth, XVth, XVIth, and XVIIth= dynasties, which is full of difficulties. Not only is the order of the succession of the kings of these dynasties unknown, but authorities differ greatly in their estimate of the length of the period of their rule. Some say that the interval between the XIIth and the XVIIIth dynasties consisted of more than 500 years, and others that it was less than 200 years. The figures given by Manetho are as follows:— =XIIIth= =dynasty.= From Thebes. 60 kings in 453 years. =XIVth= ” ” Xoïs. 76 ” in 184 (or 484 years). =XVth= ” =Shepherds.= 6 ” in 284 years. =XVIth= ” =Shepherds.= 32 ” in 518 years. =XVIIth= ” =Shepherds.= 5 (?) kings in 151 years. [Illustration: PLATE XXVII. Granite statue of King Sekhem-uatch-taui-Rā. XIIIth or XIVth dynasty, B.C. 2000. [Northern Egyptian Gallery, Bay 1, No. 276.]] [Illustration: PLATE XXVIII. Stele of the reign of Sekhem-ka-Rā, a king of the XIIIth dynasty, about B.C. 2000. [Northern Egyptian Gallery, Bay 2, No. 277.]] [Illustration: PLATE XXIX. Memorial cone of Sebek-ḥetep, a scribe, who flourished in the reign of Sebek-em-sa-f, B.C. 2000. XIIIth dynasty. [Northern Egyptian Gallery, Bay 1, No. 280.]] The total of these years is 1,590 according to one reckoning and 1,290 according to another, but it is impossible to accept either, and we must therefore assume that the total of 1,590 or 1,290 years represents the length of the reigns of the kings at Thebes, and of those who ruled in the Delta. In fact it is clear that, except at rare intervals, between the XIIth and the XVIIIth dynasties a king of the North and a king of the South were always reigning at the same time in Egypt, and that neither was sufficiently strong to make himself master of the whole country. The evidence derived from the monuments seems to indicate that the power of the Theban kings declined steadily at the beginning of this period, and that, as it declined, the power of the nomad Semites from the east, who are known as =Hyksos= or =Shepherds=, increased until the end of the period, when the Theban kings became strong enough to make themselves masters of the whole country. The names of a considerable number of kings, who may be assumed to have reigned during the XIIIth and XIVth dynasties, are known from scarabs and larger monuments, but nothing is known of their reigns.