Why should it not be reliable? Don't we rely on ancient Egyptian writings?
Yes, besides from digging through the ruins, we learn much about ancient Egypt through the eyes of ancient Egyptians. Likewise, the Old Testament is ancient Israel's account of ancient Israel. And much of it coincides with what modern historians have discovered about it.
Much about ancient Israel that does not coincide with modern history books is not history in the traditional sense to begin with. Jesus and St. Paul, for example, taught a resurrection from it contrary to what the Pharisees taught. The corporeal resurrection of the Pharisees would and should mount its truth claims on historical documentation, and it would fall short. The new life in God, on the other hand, of Christ and the apostles defies historical documentation.
If only Christians would believe the Scriptures.