The Oldest manuscripts of the Old Testament that we have date from the second century BC. The oldest complete book is the book of Isaiah in the Dead Sea Scrolls dates about 150 BC. Prior to the discovery of the Dead Sea Scrolls in 1947, the oldest complete manuscripts of the Old Testament were found in Greek manuscripts of the complete Bible, Old and New Testaments, and those date to the fourth century AD. So, you can see the discovery of the Dead Sea Scrolls pushed back the oldest discovered manuscript of the Old Testament by about 500 years.
The Oldest complete or nearly complete New Testament manuscripts are dated from the fourth century AD. But, we have much earlier portions of the New Testament. Up until recently, the earliest manuscript of any of the New Testament was the John Rylands Fragment which contained parts of five verses of John’s Gospel and is dated around 120 AD, about twenty to thirty years after the book of John is supposed to have been written.
Within the last few years a papyrus has been found with a portion of the Gospel of Mark. This was found in an Egyptian mummy mask. While the Pharoahs had masks of gold covering their faces, the nobles with less money had to use layers of papyrus sheets to create their masks. Papyrus was extremely expensive, so sheets of used papyrus were used. Some archaeologists have taken some of these masks and separated the layers with a process which enables them to read what was originally on the separate sheets. One of the sheets contains a portion of the Gospel of Mark and is tentatively dated prior to 90 AD. http://www.smithsonianmag.com/smart-news/papyrus-found-mummy-mask-may-be-oldest-known-copy-gospel-180953962/
The Gospel of Mark is believed to have been written around 70 AD. So, we have a portion of that gospel dated within 20 years of the original. This lends to the reliability of the other later manuscripts which match the new find. It also is dated within the “eyewitness period” where there are still people alive when this Egyptian manuscript was written who saw the risen Jesus, who could testify to it’s validity, and who were circulating it as far as Egypt.
Think of it this way. The assassination of John Kennedy happened in 1963, 54 years ago. There are still people alive today who were in Dallas when he was killed and could testify to any corrupt description of the events. This manuscript of Mark is within 57 years of Jesus rising from the dead. If it were not true, there were eyewitnesses alive at that time who could have refuted it. That is the value of this portion of Mark, and that is what adds validity to Easter mornings when we say, “He is risen! He is risen indeed.”
Believers Armed and Dangerous 