The last two useful pieces of information I can glean from the Hyss Valley texts are as follows: First, Tutkin and his people lived in a city called Isibis, which lies somewhere east of Hyss Valley.
Second; The spire over the north entrance to the Hyss Valley tomb is called the “Warden Stone”. It was built after Tutkin’s death, partly as tribute but partly in the hope that he would continue to watch over his people from there.
If Isibis is to the south of this monument, it makes me think that whatever Tutkin defended his people from lay to the north.
I shall be mounting another expedition to Hyss Valley, and from there I shall travel east, in the hope that I will find Isibis.