The Kings of the Middle Empire, Usertesen I, II, and III, signalised their rule by reaching out beyond the limits of Lower and Upper Egypt. They conquered Ethiopia to the south and opened up trade to the eastward with Syria, and recovered possession of the mines of Sinai. Temples were built and great public works of irrigation carried out, while changes were inaugurated in writing and education. The process of development seems to have been continued even during the Hyksos usurpation. For these Asiatic invaders, whose race and origin are unknown--the term Hyksos meaning Shepherd Kings or Bedouin Chiefs--confined their occupation to Lower Egypt, while the Egyptian Kings continued to govern Upper Egypt as vassal princes. It was an attempted interference with Egyptian self-rule that precipitated the expulsion of the Hyksos. The latter’s chief had demanded of the “Prince of the South” that he abandon the worship of Ra-Ammon for that of the Hyksos god. A refusal led to war which was brought to a successful end by Amasis or Ahmes I, first King of the Eighteenth Dynasty. With the commencement of the New Empire Egypt entered upon an era of prosperity and power that were reflected in the grandeur of her art. It corresponded in Egyptian history to the age of Pericles in Athens; the Imperial Epoch of Rome, and the High Renaissance of the sixteenth century in Italy. Amenophis subdued the Libyans to the westward of the Delta. His successor, Thothmes I, carried conquest as far south as the third cataract and annexed the land of Cush as a province. Having thus consolidated authority in the neighbourhood of Egypt, he invaded Palestine and Syria as far as the Euphrates. His daughter, Queen Hatasu, fitted out an expedition to the land of Punt (South Arabia) and brought back incense, wood, and animals, such as the dog-headed ape; all of which is duly recorded on the walls of her temple at Deir-el-Bahri. But the acme of power was reached by her half-brother, Thothmes III; for this monarch made fifteen expeditions, in the course of which he reduced the rising power of the Hittites and made himself master of the countries west of the Euphrates and south of Amanus. His two successors managed to hold together this great empire; but in time these foreign entanglements necessitated frequent expeditions. By the time of the Nineteenth Dynasty the federation of the Hittites had been consolidated and Seti I advanced against them, claiming a victory which was at least not final, for they threatened his successor, Rameses II, who, however, made a treaty of peace with them and married the daughter of the Hittite king. Rameses II also invaded Palestine and afterwards penetrated as far as the Orontes. He reigned sixty-six years and it has been estimated that half the buildings in Egypt bear his cartouche; although in many cases he probably followed the practice of adding his own cartouche to buildings already existing.