I want to know the answer to the following question:
In what century were castles first built?
All the background I'm provided with is that "The dominance of the nobility was built upon its control of the land, its military service as heavy cavalry, control of castles, and various immunities from taxes or other impositions.[S] Castles, initially in wood but later in stone, began to be constructed in the 9th and 10th centuries in response to the disorder of the time, and provided protection from invaders as well as allowing lords defence from rivals.". Is that enough to answer the question?
Answer: yes