Nag Hammadi is a region in the southern Egypt. Several farmers were one digging in hopes of finding nitrates that they could use as a fertilizer for their farms. Instead, they found a jar that contained several leather-bound papyrus writings. The farmers took the writings home with them. They recognized that some of the writings were in Coptic, an ancient Egyptian language that today is almost exclusively used in church services in Christian churches of Egypt and Ethiopia. Because of this, they decided that the writings had to do something with Christianity and gave them to a priest. Soon after that, the writings made their way to the Coptic Museum in Cairo.
The writings turned out to be a Coptic translation of Christian manuscripts originally written in the fourth century in the Greek language. The caves of the Nag Hammadi region were once home to Christian monks who lived there in solitude. Some scholars believe that the monks took the writings with them and then forgot about them or lost them. Others think that the writings were not accepted by early Christians and someone chose to hide them instead of destroying them.
The reason why so many manuscript discoveries have occurred in Egypt is very simple: Egypt has a very dry climate that doesn’t destroy the manuscripts. This doesn’t happen in the areas that are now Israel and Palestine, where the climate has just enough rainfall to make the environment not friendly to the preservation of ancient manuscripts. Being placed inside sealed clay jars was the only way for manuscripts to survive the climate of Israel or Palestine. Also, many of the Egyptian manuscripts are made of papyrus, which is very durable.
Obviously, the fact that during the first centuries of Christianity Egypt was one of the main Jewish and Christian centers also played an important role in it becoming a place of many important Christian discoveries.