As a beginning player, the area you are located in is known as "The Homeland" and it provides a safe place to learn and grow before taking your first steps in to the wider game world.  You won't be able to return to The Homeland after you relocate, but you won't be able to advance past rank 100 if you choose to stay, so eventually you will need to go to the Inner Empire.  

Knowing when the right time to move is can be tough, but here's a few tips:
  • You'll probably be able to move sometimes as soon as rank 50, but you will be able to advance to rank 80 or higher really before you begin to need resources which can only be obtained in the Inner Empire (Like Fur or Wheat).
  • Strategize with your fellow players in the city chat  about where and when to move rather than going it alone.
  • It's definitely wise to completely clear your barbarians and build up your production buildings before even considering relocating to the Inner Empire.
  • The best indicator of it being time to relocate is if your housing requires a resource you cannot get in The Homeland.
It's important to remember that you will need at least 30,000 Denarii in your Relocation Fund in order to move to the Inner Empire.