Dr. Cosmopoulos, an archaeologist and professor of Greek studies at the University of Missouri, St. Louis, said the tablet, only 2 inches by 3 inches, was a surprise uncovered last summer in the middle of an olive grove in southwest Greece, near the modern village of Iklaina. Judging by pottery in the dump, the tablet dates to sometime from 1490 to 1390 B.C. Scholars said they had little evidence before that clay tablets were made and used to keep state records so early in Mycenaean history.

Elsewhere, the Minoans on the island of Crete were keeping records as early as 1800 B.C. in an enigmatic script that predates the Mycenaean Linear B. The earliest known writing, also presumably for bookkeeping, evolved around 3200 B.C. in the Sumerian city of Uruk, in Mesopotamia. The first Egyptian writing appeared more or less at the same time.

The Missouri team had investigated the Iklaina site for 11 years, and in the last couple of summers examined the extensive evidence of stone walls of what may have been a palace at a district capital. Some walls are decorated with frescoes showing ladies of the court and ships with dolphins cavorting in water. There are also remains of a drainage and sewer system far ahead of its time.

Previous excavations had yielded clay writing tablets from 1200 B.C., close to the approximate time of the supposed Trojan War, and some references to Iklaina as an administrative center associated with Pylos. Dr. Cosmopoulos said in an interview that the new findings appeared to show that some 200 years earlier this may have been the seat of an independent chiefdom that had already achieved a degree of literacy and political organization.