Jerashan

The city of Jerashan was founded in the Sahuul Desert millennia ago, near an oasis where water from deep underground surfaces in an artesian well. The city has been continuously inhabited since that time, with some of the buildings passed down through families for generation after generation.
The oasis sits in the cup of a series of large rocky outcroppings, thrust through the sand by the same forces that created the artesian wellspring. The first buildings were adobe huts in the lee of the hills, which soon grew upward and outward, butting against the stone. The stone was soon honeycombed with more dwellings, and the adobe homes grew to several storeys tall. The core of some of the buildings dates back to the original settlement, with succeeding generations repairing, expanding, and reinforcing the structure.
Recognising the value of the water around which they built, and the risk of exhausting the source, all water supplies are carefully regulated from beginning to end. Wastewater is carried through subterranean terracotta pipes to underground settling ponds carved out of sandstone. The water gradually seeps away through the sandstone over time, eventually leaving only remnant fertilisers which can be used on the small farms which grow food and herd animals. The water itself, filtered and purified by its long travel through the stone, returns to the water currents which run far beneath the desert bedrock.
Jerashan lies on a trade route through the desert, bringing supplies and resources not available within the desert, and in turn providing a safe resting spot for the travellers and a respite from the sun beating down. The thick adobe walls and sheltering stone protect the occupants from the heat of the day and cold of the desert night.
Attempts have been made to capture both the city and the oasis over the millennia, but the original builders used a combination of adobe, stone rubble, and later stone slabs cut from the excavations, to build defensive walls. The walls were added to, growing higher and thicker, eventually forming an impregnable fortification several layers deep. Stealth and treachery have been tried in turn, but were never able to capture more than outer sections of the city - which were swiftly sealed off from access to the water, sheltered deep within the heart of the edifice. The attackers soon retreated in desperation.