Picture writing was invented in Mesopotamia before 3,000 BC. This clay tablet, dating to about 3,100 BC, has written on it a list of rations. It shows how writing was developing from using pictures to using the wedge-shaped characters known as 'cuneiform'.
The first identifiable written language is Sumerian, which is unrelated to any modern language. By 2,400 BC, cuneiform had been adapted for writing Akkadian, and later was used for writing Assyrian and Babylonian; these are all Semitic languages, as are present-day Arabic and Hebrew.
Cuneiform continued to be adapted for writing the languages of Mesopotamia's neighbours, such as Hittite and Old Persian, and was used into the first century AD. In more recent times it was deciphered in the 19th century, so that administrative, mathematical, historical, astronomical and school texts, omens, epics, letters and dictionaries can now be read by modern scholars. There are around 130,000 tablets in the British Museum.
From about 5,000 BC, stamp seals, cut with simple designs, were used to mark ownership on clay sealings on storeroom doors. They were also found on the bags, baskets etc in which goods were traded up and down the Tigris and Euphrates. Around 3,500 BC, the cylinder seal was invented; it provided room for elaborately carved designs, and could be rolled over clay.
The Akkadian greenstone seal (height 3.9cm) shown here, dating to about 2,300 BC, is shown alongside its modern impression. Gods and goddesses are depicted, identified by their horned head-dresses and attributes as a hunting god, the goddess Ishtar, the sun god Shamash and the water god Enki followed by his vizier. 'Adda, scribe' is written in cuneiform above a lion, identifying the owner as a high official, who could also have sealed letters and administrative documents on clay.