線文字A
Linear A belongs to a group of scripts that evolved independently of the Egyptian and Mesopotamian systems. During the second millennium BC, there were four major branches: Linear A, Linear B, Cypro-Minoan, and Cretan hieroglyphic. In the 1950s, Linear B was deciphered as Mycenaean Greek. Linear B shares many symbols with Linear A, and they may notate similar syllabic values. But neither those nor any other proposed readings lead to a language that scholars can read. The only part of the script that can be read with any certainty is the signs for numbers—which are, however, only known as numerical values; the words for those numbers remain unknown.