Ptah's priest /aid is in town. Ptah is in his Temple like any other God in Egypt. You follow the quests the priest gives you until you're ready to meet Ptah in his Temple.
Here's a list/chart of Egyptian Quests. If you scroll down to the most recently completed location, the next row will tell you who opens the next one for you.
For additional reference, this game has a pattern of ALWAYS needing to speak to someone, somewhere in order for new locations to open. Though the pattern can vary, seek out speakers in:
Town. Camp. Temples of the gods (even previous.) WITHIN previous mines.
Hope this helps☺