Ask the commander to interrogate her

"Go interrogate her, make sure we get all the information from her,"

The commander left with her. At a distant you hear her screaming and yelling as the soldiers inflicted pain on her to extract information.

While all that is happening, you continue examining the resources.

"Put all resources toward building granaries and houses. Develop some arrowmen to defend our city," you tell your Minister.

Just as the minister leaves, the commander enters back in, "My king. The barbarian woman was tough but we were able to crack information from her. She informed about a barbarian clan not too far from here. She was scouting our city looking to gather information before they raid us. Based on the information it looks like they do have a considerable amount of strength and might be difficult to defend if they attack first."