Sumerian Mesopotamia". Despite the importance of early Egypt–Mesopotamia relations, given the lack of direct evidence "no definitive determination has been made as to the origin of hieroglyphics in ancient Egypt". Instead, it is pointed out and held that "the evidence for such direct influence remains flimsy" and that "a very credible argument can also be made for the independent development of writing in Egypt". Since the 1990s, the discoveries of glyphs at Abydos, dated to between 3400 and 3200 BCE, may challenge the classical notion according to which the Mesopotamian symbol system predates the Egyptian one, although Egyptian writing does make a sudden appearance at that time, while on the contrary Mesopotamia has an evolutionary history of sign usage in tokens dating back to circa 8000 BCE. These glyphs, found in tomb U-J at Abydos are written on ivory and are likely labels for other goods found in the grave. Egyptian scholar Gamal Mokhtar argued that the inventory of hieroglyphic symbols derived from "fauna and flora used in the signs [which] are essentially African" and in "regards to writing, we have seen that a purely Nilotic, hence African origin not only is not excluded, but probably reflects the reality" although he acknowledged the geographical location of Egypt made it a receptacle for many influences. Elamite script The undeciphered Proto-Elamite script emerges from as early as 3100 BCE. It is believed to have evolved into Linear Elamite by the later 3rd millennium and then replaced by Elamite Cuneiform adopted from Akkadian. Indus script Markings and symbols found at various sites of the Indus Valley Civilisation have been labelled as the Indus script citing the possibility that they were used for transcribing the Harappan language. Whether the script, which was in use from about 3500–1900 BCE, constitutes a Bronze Age writing script (logographic-syllabic) or proto-writing symbols is debated as it has not yet been deciphered. It is analyzed to have been written from right-to-left or in boustrophedon. Early Semitic alphabets The first "abjads", mapping single symbols to single phonemes but not necessarily each phoneme to a symbol, emerged around 1800 BCE in Ancient Egypt, as a representation of language developed by Semitic workers in Egypt, but by then alphabetic principles had a slight possibility of being inculcated into Egyptian hieroglyphs for upwards of a millennium. These early abjads remained of marginal importance for several centuries, and it is only towards the end