Why is it important to the pueblo people to store food?

They probably needed to store it to keep it from other people or animals. Also, if there was a drought or flood, they needed a surplus of food stored to survive until farming conditions got better.

The Vikings were fierce warriors who constantly raided the shores of Frankia (France and Germany), the British Isles, Ireland, and even nowadays Russia.

They would burn and loot villages and take the materials, that they would then trade off elsewhere. They also hired troops to build armies and some even took european cities.

I believe the Frankian's economy was so damaged by the constant looting that they had to start building walls to protect their settlements