From the introduction:
Dipur is a city of the Empire of Khazistan, lying 50 miles southwest of the Kharjah Pass. It is a garrison city, as well as a stopping off point for the many caravans travelling to, or from, Susrah and lands beyond. It is often referred to as 'The Gateway to the East' by the folk of Khazistan.
It is a city built from clay bricks. These and the mortar that holds them in place are made from the mud of the banks of the Oxartus River mixed with straw collected from fields of the myriad nameless villages that dot the southern foothills of the Zorab Mountains. The city walls are not particularly high but they are broad and crenelated, patrolled by watchmen of the city's infamous Black Guard. Many of the buildings that cluster inside the walls are several storeys high and flat roofed, packed to the rafters with the urban poor of the city.
The river valley of the Oxartus is abundantly fertile and crops enough are grown to allow the feeding of the populace and for sizeable exports across the desert to Zul Bazzir.