The first inscribed tablets were purely pictographic, which makes it technically impossible to know in which language they were written, but later tablets after circa 2,900 BC start to use syllabic elements, which clearly show a language structure typical of the non-Indo-European agglutinative Sumerian language. The first tablets using syllabic elements date to the Early Dynastic I-II, circa 2,800 BC, and they are agreed to be clearly in Sumerian. This is the time when some pictographic element started to be used for their phonetical value, permitting the recording of abstract ideas or personal names. Many pictographs began to lose their original function, and a given sign could have various meanings depending on context. The sign inventory was reduced from some 1,500 signs to some 600 signs, and writing became increasingly phonological. Determinative signs were re-introduced to avoid ambiguity. Cuneiform writing proper thus arises from the more primitive system of pictographs at about that time (Early Bronze Age II).