Ancient history is the aggregate of past events WordNet Search - 3.0, "History" from the beginning of recorded human history to the Early Middle Ages or the Postclassical Era. The span of recorded history is roughly 5,000 years, with Cuneiform script, the oldest discovered form of coherent writing, from the protoliterate period around the 30th century BC.see Jemdet Nasr period, Kish tablet; see also The Origin and Development of the Cuneiform System of Writing, Samuel Noah Kramer, Thirty Nine Firsts In R..
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for the diameter of a sphere. The word "diameter" is derived from Greek language διάμετρος ( diametros), "diameter of a circle", from δια- ( dia-), "across, through" μέτρον ( metron), "measure". Online Etymology Dictionary It is often abbreviated ..