Elamite cuneiform script consisted of about 130 symbols, far fewer than most other cuneiform scripts. Europe Notational signs from ~37,000 years ago in caves, apparently convey calendaric meaning about the behaviour of animal species drawn next to them, and are considered the first known (proto-)writing in history. Cretan and Greek scripts Cretan hieroglyphs are found on artifacts of Crete (early-to-mid-2nd millennium BC, MM I to MM III, overlapping with Linear A from MM IIA at the earliest). Linear B, the writing system of the Mycenaean Greeks, has been deciphered while Linear A has yet to be deciphered. The sequence and the geographical spread of the three overlapping, but distinct writing systems can be summarized as follows (beginning date refers to first attestations, the assumed origins of all scripts lie further back in the past): Cretan hieroglyphs were used in Crete from c. 1625 to 1500 BC; Linear A was used in the Aegean Islands (Kea, Kythera, Melos, Thera), and the Greek mainland (Laconia) from c. 18th century to 1450 BC; and Linear B was used in Crete (Knossos), and mainland (Pylos, Mycenae, Thebes, Tiryns) from c. 1375 to 1200 BC. Indus Valley Indus script refers to short strings of symbols associated with the Indus Valley civilization (which spanned modern-day Pakistan and North India) used between 2600 and 1900 BC. In spite of many attempts at decipherments and claims, it is as yet undeciphered. The term 'Indus script' is mainly applied to that used in the mature Harappan phase, which perhaps evolved from a few signs found in early Harappa after 3500 BC, and was followed by the mature Harappan script. The script is written from right to left, and sometimes follows a boustrophedonic style. Since the number of principal signs is about 400–600, midway between typical logographic and syllabic scripts, many scholars accept the script to be logo-syllabic (typically syllabic scripts have about 50–100 signs whereas logographic scripts have a very large number of principal signs). Several scholars maintain that structural analysis indicates that an agglutinative language underlies the script. Mesopotamia While research into the development of writing during the late Stone Age is ongoing, the current consensus is that it first evolved from economic necessity in the ancient Near East. Writing most likely began as a consequence of political expansion in ancient cultures, which needed reliable means for transmitting information, maintaining financial accounts, keeping historical records, and similar activities.