Joshua 2:10 (ESV)

10 For we have heard how the LORD dried up the water of the Red Sea before you when you came out of Egypt, and what you did to the two kings of the Amorites who were beyond the Jordan, to Sihon and Og, whom you devoted to destruction.

The people of Canaan had heard about the power and majesty of the Lord God. They’ve heard how he parted the Red Sea and destroyed the army of Pharaoh. Even though that event took place more than forty years ago by the time the spies entered Jericho, it was still talked about in the pagan world. Then, the people of Jericho also heard that two powerful kings, with strong armies and fortified cities, have also been defeated by this same God.