Arendia is the country of the people of the god Chaldan in the David Eddings book series The Belgariad and The Malloreon. It consists of two duchies, Mimbre and Asturia, though there used to be two more as well: Wacune and Erat. The war of the three duchies† is one of the darkest periods of Arendish history. The only thing that united the kingdom was the annihilation of Vo Wacune by the Asturians in 2943, and the later destruction of Vo Astur by the Mimbrates in 3793, resulting in the Mimbrate-dominated monarchy being sovereign over Arendia.
The nation is a kingdom with the throne jointly held by the king and queen, who are also the duke of Mimbre and the duchess of Asturia. Due to the delicate political balance, the king and queen give up their given names to rule as Korodullin and Mayaserana, the names of the first Arendish monarchs, in order to promote greater unity. There has also been an excessive degree of inbreeding to preserve the familial ties. Though technically these two duchies are equals, Mimbre treats Asturia as a vassal state until the end of The Belgariad.
The major reason behind the discontent between the supposedly equal Duchies was a refusal by the Mimbrates to recognize Asturian titles after the formal unification. The conflict arose over the requirement that the Asurians swear an oath to the new King and their previous oath to the original Duke of Asturia. As the Queens of Arendia - in the closely interbred Royal line - were direct decedents of the Duke, then the Asturians' oath was still very much in force. The current Queen of Arendia (in her capacity as the Duchess of Asturia) released all Asturians from the oath, at which point they swore their oath of allegiance to the King of Arendia (but not to the Duke of Mimbre though technically he is the same person as the King). With this issue solved, it is presumed that all Asturian titles were formally recognized. Indeed Asturians such as Lelldorin then freely started to throw themselves into formally 'Mimbrate only' internal conflicts and were welcomed 'to the party' just as quickly.
Arendish society is feudal, built on the institution of serfdom. Rival lords seem to be continually skirmishing, and when they are not, they are holding tournaments during which they hone the skills used for skirmishing. Arends are typically viewed as not too bright and sometimes overly proud, though they are universally hailed as being loyal and brave. Unlike the gods of some other peoples, Chaldan does not intervene much in human affairs.
Asturia lies in the forested north and west portions of Arendia, bordering Sendaria and the Sea of the Winds. Asturian patriots engage in guerilla warfare against their Mimbrate overlords. Despite vigorously protesting Mimbrate oppression, they fail to see their own oppression of the serfs in their country.
Many among the Asturian nobility are renowned archers. Serfs are used to provide support.
Erat was given to Polgara because of her services to Arendia in creating peace for a time. Erat was the far north part of Arendia in Wacune before Polgara acted to create Sendaria from it after the Asturians smashed Vo Wacune, which creation was protested by the other dukes. These changes included abolishing serfdom, a rent system for property owning, creating schools and the establishment of the now-renowned Sendarian values (courtesy, common sense, sobriety, etc.). She later asked the Tolnedrean Emperor, a Borune, to create Sendaria.
† Erat had strong ties with Wacune, but couldn't aid it against the Asturians, though they did defend their own land, with Polgara controlling the battles and communicating with her generals with her mind.
Mimbre lies in the south, bordering on Tolnedra and Ulgo. Mimbre refused to recognize titles of Asturian nobility, and defended against insurgencies by Asturians until the end of The Belgariad when the Asturians swore the required oath of allegiance to the King of Arendia (rather than the Duke of Mimbre). With Mimbre recognising the titles of the Asturian's, a much better degree of equity was established between the Duchies.
Mimbrate forces typically fight as heavy cavalry, with armored knights riding armored warhorses and 'men at arms' supporting them, often with pikes and siege engines. Serfs provide support, mostly as cannon fodder in attacks.
Wacune historically formed the north and west section of the country, before being destroyed by Asturia during the Arendish Civil War. Large portions of Wacune were absorbed into Asturia, though some portions joined Erat in forming Sendaria, ending the Wacite duchy. Wacune is heavily forested and adjoins the foothills of the Ulgo mountains. Sometimes Algroths descend from the mountains to hunt, and can be dangerous to travelers in this region.