NEW YORK, NY.- Almost 100 years ago, a group of Jewish linguists and historians decided to create a “scientific institute” that would collect literary manuscripts, letters, theater posters, business records and ephemera so they could document the flourishing Yiddish culture of Eastern Europe and promote the language.

Among its honorary board members: Albert Einstein and Sigmund Freud.

Within 15 years, the institute, established in the Lithuanian city of Vilnius (Vilna in Yiddish), had blossomed into the world’s leading archive of Eastern European Jews and their scattered emigrant satellites. Its inventory of artifacts testified to how they lived, loved, worked and played through the words and possessions of common folks as well as such luminaries as Einstein, Theodore Herzl, Sholem Aleichem and Martin Buber.

But in 1941, the invading Nazi-led Germans ransacked the institute and began to destroy much of the collection, sending off some of what they viewed as the most significant items to a center near Frankfurt, Germany, to study what they predicted would be an extinct race.

Substantial remnants of the prewar collection were recovered piecemeal over the years, often in remarkable ways. Some scholars, for example, slipped documents into their clothing then hid them away in attics to avoid destruction at the hands of the Nazis. For decades, the surviving artifacts have been stored in separate, independently operated archives in New York and Vilnius. But, starting Monday, through the alchemy of digitization, 4.1 million pages that record the entire surviving prewar collection now held in both locations will be made available to scholars and the interested public worldwide.

The reuniting of the materials online followed generally amicable negotiations between what is now known as the YIVO Institute of Jewish Research, in Manhattan, and the government of Lithuania, which was determined to hold onto the original documents as part of its national heritage.

“Now, finally, this veritable gold mine is united, virtually, opening for the scholar and the general reader knowledge about a vanished world immeasurably more accessible because of this new extraordinary resource,” Steven J. Zipperstein, a professor of Jewish history at Stanford University said in a statement released by YIVO. Using YIVO’s resources, he wrote a definitive study of the 1903 pogrom in the then Russian city of Kishinev in which 48 Jews were killed and numerous women raped.

The digitization process took seven years and cost $7 million, most of it contributed by donors led by Edward Blank, a telemarketing pioneer for whom the digital collection is named.

Among its notable pieces are a diary handwritten by Herzl, a founder of modern Zionism; pages from S. Ansky’s handwritten Yiddish manuscript of his classic play “The Dybbuk”; letters from Einstein to writers and theater folk; witness accounts of pogroms in Russia, Poland, Ukraine and Belarus; business and personal papers of the Rothschild family; Yiddish songs about love, crime, drinking and Stalin; etchings by Marc Chagall; and a homespun astronomical dial that calculates when religious holidays would fall.

The prewar collection was restored in several ways, most notably through the work of the “Paper Brigade” — a group of 40 poets and intellectuals. Forced by the Nazis to winnow out the jewels of the archive for a planned German institute for “the study of the Jewish Question,” the scholars in the Brigade hid precious books and documents in their clothing and squirreled them away in attics and underground bunkers. After the war, those who survived the Holocaust recovered the materials from their hiding places.

The trove that made its way to Frankfurt was recovered by Allied soldiers and art experts known as the Monuments Men, who shipped it to YIVO’s new headquarters in New York. And when the Soviet Union absorbed Lithuania and sought to destroy anything that smacked of ethnic chauvinism, a librarian, Antanas Ulpis, who was not Jewish, hid YIVO materials in the basement of a Catholic church. They were discovered there in 1991 and 2017.

Though the artifacts remain in Vilnius, they will be accessible virtually through the website: vilnacollections.yivo.org.

This article originally appeared in The New York Times.