There are three ways that we know what happened in history:

1. Oral tradition was the most common method of passing on events, legacy and stories. During a campfire talk or a teaching lesson, the student/listener was expected to listen and pass the story on. They listened very carefully because they knew the information was not written down some where or recorded on a web site.  They recall skills were much sharper than ours.
2. Historical records left by historians, writers, political/religious groups or just every day people. These are written down on papyrus, in books, stone tablets. Many cultures like the Egyptians, Greeks and the Romans recorded events to show off their successes.
3. Archaeological evidence found in ruins give clues to the culture and life of ancient people.

Each of these methods help to support the Bible. While the Bible started as an oral testimony, prophets and apostles recognized it needed to reach a bigger audience. Their words were preserved and written down. The people and places detailed in the Bible have been also been confirmed in archaeology and the historical records of civilizations outside the Jewish community.