The Dead Sea Scrolls refers to a set of leather manuscripts and papyri discovered in caves and ancient ruins of the Wilderness of Judea.  The first of these discoveries took place in 1947 when a group of shepherd boys stumbled upon a group of scrolls in a cave not far from the ancient site of Khirt Qumran. 

Upon examination of the documents, they have been said to originate from a library of an ancient Jewish community which flourished before and comtemporary with the birth of Christianity.  Right now, over 500 manuscripts have been found in different caves within the vicinity. 

Although we do not know for certain that the Dead Sea Scrolls are being followed in the Evangelion series, there are several hints within the documents that traces the origins of the Evangelion universe in the scrolls.  Among them are the mentions of Adam (which caused the destruction of mankind), Angels and Children of Light.