Describe the setting of the given narrative in detail.
Once upon a time, there were two princes who were best friends.
The setting of the given narrative is not specified in the provided sentence. Only the main characters, two princes who were best friends, are introduced. More details are required to accurately describe the setting.
Complete the following task based on the instruction and optional input provided.### Instruction:
Describe the setting of the given narrative in detail.

### Input:
Once upon a time, there were two princes who were best friends.

### Output:
The setting of the given narrative is not specified in the provided sentence. Only the main characters, two princes who were best friends, are introduced. More details are required to accurately describe the setting.