The measure stuff type of ruler, not the political kind. Oh, and also were particularly accurate rulers considered valuble/expensive?
In my main area of study, the Near East, rulers were of course vital to architectural planning. Many great city-states and Empires built large walls, large temples, and indeed enormous cities. Of course that required planning, and plans in detail would require a standardised straight edge. You ask a good question, how accurate were they? Well, they had an unusual method of standardising their ruler sizes that lasted for many centuries- they used the length of Gilgamesh's left ulna, allegedly, as their standard length. A skeletal arm was kept in Uruk, which was actually a major city in the Near-East comparable to Babylon for much of its history, and there the ruler-makers would travel when a new one was required. Gilgamesh's arm would be reverently extracted from its resting place, and then the wood/bronze/bone ruler would be carved directly against the proportions of the ulna. Now, as you can imagine for large bureaucracies constantly getting through rulers, this became something of a problem. But they solved this by having dedicated workshops for rulers in Uruk itself, right next to the temple of Anu in which the skeletal arm was kept. However, this did introduce problems- the bone was slowly splintered by various accidents, and even slight chips would cause a change in the standardisation of all the other rulers. By the Bronze Age collapse c.1200 BC the practice was increasingly untenable, and then disaster struck- the Arameans stole Gilgamesh's bone. However, the last ruler made from his arm was then used as the template to make rulers now standardised by smelting into moulds and sanding off the edges, and though ruler's were still known by the poetic name of 'The Reach of Gilgamesh' they were no longer based on the skeleton of their ancient and mighty ruler.
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