All new players start with a 'bubble' that protects them from attack or other player's Nobles entering their Keep.
Use this time to build up your kingdom, family and defenses.
 
Some actions can 'pop' the bubble early, such as:
  • Attacking another player
  • Reinforcing an attack against another player
  • Sending your Nobles to another player's Keep
  • Capturing another player's Nobles
  • Relocating your city to a location with a resource bonus, such as a Woodside or Capital
There is no way to re-bubble your city, once the bubble has popped it's gone forever.