The Sumerian civilization dwindled approximately 3500 years ago, replaced by peoples from the North and East; a replacement that was often the result of war. There are several lament texts that have been found, each mourning the destruction of a different Sumerian city. These texts are all from the same time period, causing one to wonder if the laments are simply reflections of humans at war, or truly those of wars of the Gods themselves - quarreling over their own ideologies.
http://www.gatewaystobabylon.com/myths/texts/lamentations/lamentur.html
excerpt:
(Great) fires he lit that heralded the storm. The people mourn.
And lit on either flank of furious winds the searing heat of the desert.
Like flaming heat of noon this fire scorched.
The storm ordered by Enlil in hate, the storm which wears away the country,
covered Ur like a cloth, veiled it like a linen sheet.
On that day did the storm leave the city; that city was a ruin.
O father Nanna, that town was left a ruin. The people mourn.
On that day did the storm leave the country. The people mourn.
Its people(’s corpses), not potsherds,
littered the approaches.
The walls were gaping;
the high gates, the roads,
were piled with dead.
In the wide streets, where feasting crowds (once) gathered, jumbled they lay.
In all the streets and roadways bodies lay.
In open fields that used to fill with dancers,
the people lay in heaps.
The country’s blood now filled its holes, like metal in a mold;
bodies dissolved — like butter left in the sun.
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