I’m not altogether sure what Abu Simbel in the 13th century BC was used for. Whether such rituals as I describe here really did take place. It is, admittedly, a bit of pseudo history. But Doctor Who has always been famous for that.

Science fiction already HAS aliens pretending to be Egyptian gods, too. Hathor is, as it happens, one of the Go’uld who plague the heroes of Stargate SG1. But that couldn’t be helped. The ‘real’ Hathor is the Goddess to which Nefatari’s temple at Abu Simbel is dedicated, and so it had to be Hathor demanding the handmaidens.

Naturally, Chrístõ knows its all hogwash. He knows it’s a projection of some sort. But he has to convince the people of Abu Simbel that it is. His plan almost comes unstuck, as such plans are wont to do. But in the end, with a little help from his TARDIS, he does it.

The TARDIS being able to disguise itself as different things comes in handy in this story. The royal barge is its first disguise. The fourth time now it has been a boat. On the alien ship it is simply a portal through which the handmaidens are assured safety lies. Then it gets to show off a bit with the fiery curtain that convinces the people that Chrístõ is, indeed, more powerful than their gods.

The names Chrístõ chose, incidentally, are authentic ancient Egyptian. Athribis is a town further down the Nile. Prince Tepemkau, Prince Menmaatre and the princesses Sithathor and Nodjmet are perfectly in keeping with the period. And they DO roughly mean what Terry and Cassie said they meant in the story.

Tepemkau - The Best of Souls.
Menmaatre - Eternal is the justice of Re
Sithathor - daughter of Hathor
Nodjmet - the sweet one.

Unfortunately the very detailed website I found on Google to construct these names is no longer available. These below are two less detailed sites which give an idea of how the names are constructed.

http://www.touregypt.net/featurestories/names.htm
http://terraflex.co.il/ad/egypt/glossary.htm