The scale: roughly 900 scrolls, and how old they are

"The Dead Sea Scrolls" is shorthand for a whole library, not a single book. From the eleven Qumran caves came the remains of about 900 separate manuscripts, most of them not whole scrolls but thousands of leather and papyrus fragments, some tens of thousands of pieces, that scholars have spent decades sorting and joining, a little like reassembling shredded documents. The great majority are written in Hebrew, a good number in Aramaic (the everyday language of the region), and a few in Greek; almost all are on treated animal skin or papyrus, with one famous outlier, the Copper Scroll, incised on metal, listing hidden treasure. By studying the handwriting (palaeography), and later confirming it with radiocarbon dating, scholars place the copies across roughly three centuries, from about 250 BC to AD 68, the last date set by history, because the Roman army destroyed the Qumran settlement during the First Jewish Revolt in AD 68, and the scrolls were evidently hidden in the caves just before. That age is the headline. Until 1947 the oldest substantial Hebrew manuscripts of the Old Testament were medieval, the great Masoretic codices copied around AD 900–1000. The Qumran biblical scrolls pushed the physical evidence back a thousand years, into the centuries before Christ.