"It is quite possible to propose a hypothesis that the “Linear A” attested before some particular date in the 17th century BCE (i.e., between 1700 and 1600 BCE) may have had a significantly different linguistic base than the Linear A attested after that date.It would be quite difficult to refute such a hypothesis, since so little of the older Linear A exists, and that which does contains so few words and signs."
Linear A

January 1, 1970