Manethos was an egyptian high priest.the person who wrote this was a "jew".

The first writer upon whom I shall dwell is one whom I used a little earlier witness to our antiquity. I refer to Manetho. This writer, who had undertaken to translate the history of Egypt from the sacred books, began by stating that our ancestors came against Egypt with the inhabitants; and then he himself admitted that at a later date again they were driven out of the country, occupied what is now Judaea, founded Jerusalem, and built the temple. Up to this point he followed the chronicles: thereafter, by offering to record the legends and current talk about the Jews, he took the liberty of interpolating improbable tales in his desire to confuse with us a crowd of Egyptians, who for leprosy and other maladies had been condemned, he says, to banishment from Egypt. After citing a king Amenophis, a fictitious person,—for which reason he did not venture to define the length of his reign, although in the case of the other kings he adds their years precisely,—Manetho attaches to him certain legends, having doubtless forgotten that according to his own chronicle the exodus of the Shepherds to Jerusalem took place 518 years earlier. For Tethmosis was king when they set out; and, according to Manetho, the intervening reigns thereafter occupied 393 years down to the two brothers Sethos and Hermaeus, the former of whom, he says took the new name of Aegyptus, the latter that of Danaus. Sethos drove out Hermaeus and reigned for 59 years; then Rampses, the elder of his sons, for 66 years. Thus, after admitting that so many years had elapsed since our forefathers left Egypt, Manetho now interpolates this intruding Amenophis. This king, he states, conceived a desire to behold the gods, as Or, one of his predecessors on the throne, had done; and he communicated his desire to his namesake Amenophis, Paapis’ son, who, in virtue of his wisdom and knowledge of the future, was reputed to be a partaker in the divine nature. This namesake, then, replied that he would be able to see the gods if he cleansed the whole land of lepers and other polluted persons. The king was delighted, and assembled all those in Egypt whose bodies were wasted by disease: they numbered 80,000 persons. These he cast into the stone-quarries to the east of the Nile, there to work segregated from the rest of the Egyptians. Among them, Manetho adds, there were some of the learned priests, who had been attacked by leprosy. Then this wise seer Amenophis was filled with dread of divine wrath against himself and the king if the outrage done to these persons should be discovered; and he added a prediction that certain allies would join the polluted people and would take possession of Egypt for 13 years. Not venturing to make this prophecy himself to the king, he left a full account of it in writing, and then took his own life. The king was filled with despondency. Then Manetho continues as follows (I quote his account verbatim): “When the men in the stone-quarries had suffered hardships for a considerable time, they begged the king to assign to them as a dwelling-place and a refuge the deserted city of the Shepherds, Auaris, and he consented. According to religious tradition this city was from earliest times dedicated to Typhon. Occupying this city and using the region as a base for revolt, they appointed as their leader one of the priests of Heliopolis called Osarsêph, and took an oath of obedience to him in everything. First of all, he made it a law that they should neither worship the gods nor refrain from any of the animals prescribed as especially sacred in Egypt, but should sacrifice and consume all alike, and that they should have intercourse with none save those of their own confederacy. After framing a great number of laws like these, completely opposed to Egyptian customer, he ordered them with their multitude of hands, to repair the walls of the city and make ready for war against King Amenophis. Then, acting in concert with certain other priests and polluted persons like himself, he sent an embassy to the Shepherds who had been expelled by Tethmosis, in the city called Jerusalem; and, setting forth the circumstances of himself and his companions in distress, he begged them to unite wholeheartedly in an attack upon Egypt. He offered to conduct them first to their ancestral home at Auaris, to provide their hosts with lavish supplies, to fight on their behalf whenever need arose, and to bring Egypt without difficulty under their sway. Overjoyed at the proposal, all the Shepherds, to the number of 200,000, eagerly set out, and before long arrived at Auris. When Amenophis, king of Egypt, learned of their invasion, he was sorely troubled, for he recalled the prediction of Amenophis, son of Paapis. First, he gathered a multitude of Egyptians; and having taken counsel with the leading men among them, he summoned to this presence the sacred animals which were held in greatest reverence in the temples, and gave instructions to each group of priests to conceal the images of the gods as securely as possible. As for his five-year-old son Sethos, also called Ramesses after his grandfather Rapses, he sent him safely away to his friend. He then crossed the Nile with as many as 300,000 of the bravest warriors of Egypt, and met the enemy. But, instead of joining battle, he decided that he must not fight against the gods, and made a hasty retreat to Memphis. There he took into his charge Apis and the other sacred animals which he had summoned to that place; and forthwith he set off for Ethiopia with his whole army and the host of Egyptians. The Ethiopian king, who, in gratitude for a service, had become his subject, welcomed him, maintained the whole multitude with such products of the country as were fit for human consumption, assigned to them cities and villages sufficient for the destined period of 13 years’ banishment from his realm, and especially stationed an Ethiopian army on the frontiers of Egypt to guard King Amenophis and his followers. Such was the situations in Ethiopia. Meanwhile, the Solymites [or dwellers in Jerusalem] made a descent along with the polluted Egyptians, and treated the people so impiously and savagely that the domination of the Shepherds seemed like a golden age to those who witnessed the present enormities. For not only did they set towns and villages on fire, pillaging he temples and mutilating images of the gods without restraint, but they also made a practice of using the sanctuaries as kitchens to roast the sacred animals which the people worshipped; and they would compel the priests and wards casting the men forth naked. It is said that the priest who framed their constitution and their laws was a native of Heliopolis, named Osarsêph but when he joined this people, changed his name and was called Moses.”