The tombstone, which is made of sandstone and is roughly the size of a legal pad, became their window to an ancient world centered in Zoar. Dr. Fine said that Zoar was “a major Christian city, a biblical pilgrimage city,” but that it had a sizable Jewish population. Hershel Shanks, the founder and editor of Biblical Archaeology Review and an influential scholarly figure on the Dead Sea Scrolls, agreed that such a tombstone “represents a Jewish community that thrived there.”

“It’s a very little known part of Jewish history which archaeology resuscitates,” Mr. Shanks said.

The students knew that Jewish tombstones from Zoar had been discovered in the early 20th century; Dr. Fine said 30 to 40 had been documented. Far more Christian tombstones have been found, and he said there were differences between the ways Christians and Jews remembered their dead. The Christian tombstones were inscribed in Greek, and most carried common Christian symbols — a cross, a fish or birds. Dr. Fine said the lettering on the Jewish ones was in a form of Aramaic that only Jews, not Christians, were taught to read. The symbols, as might be expected, included menorahs.

From the beginning, the Yeshiva students were confident they could make sense of the Aramaic inscriptions; Talmudic Aramaic is virtually the same as the Aramaic on the tombstone. They also know Hebrew. Mr. Friedman said the first few words were straightforward, and Ellie Schwartz, a senior, recited them: “ ‘Here rests the soul of Sa’adah, daughter of something.’ We don’t know the ‘something.’ ”

Going by the format of other ancient tombstones, they felt certain the missing word was the name of the woman’s father and wondered if it was Phineas, but they said they could not be sure. “We have the P,” Dr. Fine said. “We thought there was an N, but we’re stuck because whatever it is, it’s been scratched away. You get to the point where ‘I can’t know’ may be the most learned answer you can give.”

If the father’s name was elusive, so was another basic fact about the woman, whose name means “divine help.”

“They don’t mention her age,” Mr. Friedman said. Dr. Fine said Christian tombstones from that area carried ages, but Jewish tombstones did not. That was simply the custom of the day, he said.

But the students could date the stone, based on the parallel dating systems inscribed on it. One referred to the Temple in Jerusalem, destroyed by the Romans in the year 70. (That system was used by Jews in Greece until World War II, Dr. Fine said; the last place the system was used, he said, was Corfu, before the Nazis rounded up the Jews who lived there and sent them to Auschwitz.) The other system was based on the number seven. By comparing the two systems, they could say with certainty that she died 362 years after the destruction of the temple.