From about 2500 B.C. the first large civilizations arose 

 in the Near and Far East, these being centered on the 

 great river valleys of the Nile in Egypt, of the Tigris- 

 Euphrates in Iraq (Mesopotamia), and of the Yellow 

 River in China. Smaller, but later contributing to the 

 major, civilizations arose in Europe (Crete) and India 

 (Indus river valley). While in South America there arose 

 the Aztecs and Incas, but these were cut off from any 

 interaction with the remainder of humanity. 



The Tigris-Euphrates civilization, with its great cities 

 of Babylon and Ur, irrigated the river valleys, invented the 

 first form of writing — the cuneiform on clay tablets — 

 and devised the sexagesimal system of mathematics (it 

 being thought at first that there were 360 days in a year, so 

 that the circle was divided into 360 degrees). The indi- 

 vidual cities were at first separate states (the Sumerian 

 City States), but later united to form the Babylonian 

 Empire. By 1700 B.C. they had an efficient system of gov- 

 ernment and law, and had discovered iron smelting. By 

 1100 B.C. they had conquered the Eastern Mediterranean 

 peoples, and these Assyrians governed from a new capital 

 at Nineveh. The Assyrian king Ashurbanipal collected 

 the first library of 20,000 tablets, about 700 B.C. In 600 

 B.C. the prophet Zoroaster taught a religion based on a 

 God of Light — this was adopted by Cyrus, who founded 

 the Persian Empire extending from the Indus to the Nile, but 

 this empire was destroyed in 320 B.C. by the Greek, 

 Alexander the Great. 



The Egyptian civilization, one of the greatest the 

 world has ever known, produced the earliest large build- 

 ings of precise geometric shape — the Pyramids at Gizeh. 

 This required a considerable advance in trigonometry — 

 this branch of mathematics developed with the need to 



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