The development of cities and agriculture led to the growth of commerce. In one of these cities, and for hundreds of years, Sumerian merchants kept records of what they sold and bought on clay tokens in the shape of animals, jars, and other items they traded.To keep track of sales they covered the chips with mud that they scraped off with the end of a cane. Towards the year
3300 BC, they realized that they did not need figures and began to scratch with simplified signs on whatever surface represented the articles - that was the beginning of writing. As the canes left marks in the shape of a triangle or wedge, this type of writing is known as "cuneiform". When they wanted to keep track of the sales, they made it in clay and baked it.
