Why Are Ancient Cities on Hills? They Built the Hill Themselves
By the BrainSnail editorial team. How these articles are written and checked, and how to tell us when one is wrong.
A flat-topped mound rising from a plain in the Middle East is usually not a natural hill but the accumulated debris of a settlement rebuilt on its own rubble for thousands of years.
How a mound accumulates
Building in mud brick means building in a material that dissolves. A wall lasts a few decades before needing replacement, and the usual practice was to knock the old structure down, level the rubble where it stood and build the new house on top, since carting debris away was labour nobody would spend. Each rebuilding therefore raised the ground level slightly, and over a few thousand years of continuous occupation the settlement climbed steadily upward on its own remains. Rubbish, ash, collapsed roofs and abandoned floors all contribute. Mounds twenty and thirty metres high exist, and some contain more than twenty distinct settlement levels.
Why they were reoccupied
Settlement returned to the same spot repeatedly for practical reasons:
- •A reliable water source, which does not move
- •Command of a route, a ford or a pass
- •Good land within walking distance
- •Height itself, which is defensible and above flooding
- •Existing walls and foundations worth reusing
- •Established ownership and the weight of habit
What the layering gives archaeologists
A site where each period sits directly on the one before it is close to ideal evidence, and the discipline of excavation was largely developed on exactly these mounds. The vertical sequence establishes which occupation is older than which without any dating method at all, purely from position. Changes in pottery style through the sequence can then be tied to that order, producing a relative chronology that can be applied at other sites. Destruction layers of burning and collapse mark violent events and can sometimes be matched to historical records. And because material was buried rather than cleared, the ordinary objects of daily life survive in quantity in the floors and fills.
Where they are found
The distribution of these mounds maps onto where mud brick was the standard building material, which is the dry belt running from the eastern Mediterranean through Mesopotamia into Iran and central Asia, with thousands recorded across Syria, Iraq, Turkey and the Levant. Comparable mounds occur in the Indus valley and in parts of eastern Europe and the Balkans. The local words for them differ and several appear in place names, which is why so many modern village names in the region begin with the word. Where stone was the usual material, as around much of the Mediterranean, settlements did not accumulate the same way and ancient sites are far harder to spot from a distance.
Why digging them is difficult
The same feature that makes these sites valuable makes them painful to excavate. Reaching an early level means removing everything above it, which destroys those later levels permanently, so an archaeologist must choose which periods to sacrifice. Early excavators dug enormous trenches straight down and were criticised heavily for it afterwards. Mud brick is extremely hard to distinguish from the mud brick debris it sits in, so walls can be dug through without being noticed, which happened repeatedly in early work. Pits and foundations from later periods cut down into earlier ones and mix the material. And the sheer volume of earth means that only a tiny fraction of any large mound has ever been examined.
The takeaway
Mud brick buildings were levelled and rebuilt on their own rubble rather than cleared away, so a continuously occupied settlement climbed upward on its own debris, producing flat-topped mounds up to thirty metres high with twenty or more occupation levels. The vertical order establishes chronology without any dating method. Reaching an early level destroys every later one above it, which forces a permanent choice about what to sacrifice.