The Epistle of Jude, at verses 14 and 15, quotes a prophecy of the Lord coming with his holy myriads to execute judgement, attributes it to Enoch the seventh from Adam, and thereby quotes what stands at 1 Enoch 1:9. This is the clearest case in the New Testament of a canonical letter citing a book that no major church would later canonise, and it is a plain textual fact rather than an inference. Jude's angels kept in chains, and the parallel in 2 Peter, draw on the same Watchers material.
Early Christian writers used the book freely. Tertullian defended its authority and blamed the Jews for rejecting it. Others were less comfortable, and from the fourth century onward it disappeared from Greek and Latin use. Rabbinic Judaism gave it no standing at all. By the medieval period the West knew it only through quotations, and its survival was assumed to be a rumour.
Recovery came through Ethiopia. The Scottish traveller James Bruce returned from Ethiopia in 1773 with Geez copies: one went to the royal library in France, one to the Bodleian at Oxford, one he kept, and a further manuscript reached Rome and is now in the Vatican. Richard Laurence published the first English translation in 1821.
In the Ethiopian Orthodox Tewahedo Church, and in the Eritrean Orthodox Tewahedo Church, 1 Enoch was never lost and is not an object of curiosity: it is canonical scripture, read and cited as such, part of a canon wider than the Catholic, Orthodox or Protestant Old Testaments. Beta Israel tradition holds it in the same regard. Elsewhere it is classed as pseudepigrapha, which describes its status in those communities accurately without describing its status in Ethiopia at all.