Arland (also called the Republic of Arland or the Arland Republic) is one of the main locations throughout the Arland Series, first mentioned in Atelier Rorona: The Alchemist of Arland.
Arland is the capital (and also largest) city that exists within Atelier Rorona, Atelier Totori and Atelier Meruru. Even if Arland is not the main city within a game, it still holds importance in each game within the Arland series.
In Atelier Rorona Arland is still a kingdom, and appears to be a large power in the world. It is run by the the king and his advisors, most notably Governor Meredith, tasked with shutting down Rorona's workshop.
During the gap in time between the events of Atelier Rorona and Atelier Totori the Kingdom of Arland has become a Republic, and is now referred to as the Republic of Arland. It gathered surrounding villages, such as Alanya, and combined them to become a republic. Because of this event, Sterk lost his position as a knight, and Gio no longer has position as a King.
The city of Arland does not appear within the game itself, but heavily influences the main story. The game focuses on Arls, a rural kingdom that is preparing to merge with the Arland Republic. The merger is scheduled to take place 3 years from the start of the game's events (five years if given an extension), and it is the goal of Princess Meruru to expand her kingdom for the final merger through alchemy and adventuring.
If she succeeds in her goals by growing the population to at least 100,000, the final scene before the game's closing credits will featuring the merger of Arls into the Arland Republic. Gio and Lord Dessier (in his final act as a king) will announce the merger.