As Christianity became the state religion of the Roman Empire, laws against heretical groups intensified. For example, Bishop Athanasius's 367 CE Easter letter outlined the 27 books of the New Testament and rejected non-canonical writings, contributing to an atmosphere where possessing forbidden books became dangerous.

In 1945, Coptic monks' hidden library of 13 leather-bound papyrus codices was uncovered near Nag Hammadi, Egypt. Historians believe these texts were buried around the 4th or 5th century to save them from destruction during purges of heretical or non-canonical literature.