Around 1720-1710 BCE, Egypt began to be invaded by a people "of obscure race",
who became known as the Hyk-Sos, "shepherd kings".
These Hyksos melted easily into Egyptian society at first; eventually they became very powerful,
and finally, in a coup, they came to rule the whole of Northern Egypt,
imposing one of their people as the legitimate Pharaoh.

They were able to accomplish this because they took advantage of a time when the dynasty of Pharaohs
came to an end, because the Pharaoh had no son to succeed him.
This was usually the sign of the end of a dynasty and the beginning of another,
although there are exceptions; Hatshepsut was not considered the end of a dynasty,
whereas Ahmose is considered the first king of the 18th dynasty
because he reconquered Upper Egypt from the Hyksos, although his father was also Pharaoh.

During the Hyksos rule of Upper Egypt, they established their capital in the city of Avaris in the Delta,
and the legitimate line of Pharaohs had to move to Thebes (now Luxor) in the South, ruling only over Lower Egypt.

For about a hundred years, there was relative peace and cooperation between the two Pharaohs,
simply because the Hyksos were really very good rulers,
knowing how to adopt and improve the Egyptian lifestyle.

But naturally, there were undercurrents of enmity. The Hyksos Pharaohs were always desperate to prove their (non-existent, really)
legitimity, and furious because the true secrets of king-making were never delivered to them. They adopted traditional Egyptian
names, and yet curious ones; Apophis (Apepi) for example is the other name of Seth, the evil brother who slew Osiris.