An is the first of Sothis' trio of southern sister cities, along with Tephu and Wati. It was founded in -107 AR by Pharaoh Hirkoshek I as a worker city housing the laborers and artisans working to construct his pyramid.1
The City of Triangles is so-called because of the similar shapes of distant Mount Na-Ken and the surrounding peaks, as well as the pyramids visible on the southern horizon. Aside from the pyramid of Hirkoshek I, the region also holds the pyramids of Hirkoshek II, Zahur I, and Kamaria the Brazen.1 Kamaria's pyramid, thought plundered long ago, continues to attract followers of the cult of Rovagug, and some whisper that there may be unopened levels beneath those already explored.2
For additional as-yet unincorporated sources about this subject, see the Meta page.