The Grand Duchy of Arlathan, commonly referred to as Arlathan or simply as Artha, is one of the 11 constituent states of the Aquitanian Empire and is also the oldest. Arlathan is known for being the craddle of the Aquitanii Civilisation and later, birthplace of Tridius Wolfkehr, the father of Aquitania. Arlathan was the first state to proclaim its independence from the Sevintrian Imperium in the year 397CE, immediately after Kalenhad's miracle victory in the Battle of the Weißfluss, in which the last Sevintrian Army was destroyed and Arlathan consolidated. Tridius then assisted other Kingdoms in expelling the Sevintrians in several campaigns that culminated in the total defeat of the Magisterial Forces in the year 402.
The name Arlathan is assumed to have its origins in the mythical home of the Old Gods: Arlathan, which in itself means Realm of Artha in Aquitanii. The name was kept, but shifted constantly between Aquitania, and Arlathan, as the Arlathanians believed they were the sole successors of the Aquitanii Imperium, which flourished in the region.