The first King of Aruthien was a Paladin of Kath who rose up in opposition to Nagul in what was once Isten. Aruthien was advised by an elderly wizard of little power called Thadus. Aruthien's rebellion began as a successful accident - Aruthien and Thadus were discovered in the village of Tir Casta by Nagul's forces, and were corned into a fight. They killed half the garrison defending a ruined stable, and roused the rest of the village into rebellion. Advised by his wily old wizard, and aided by the Elven hero Aiur, Aruthien roused the whole Kingdom in rebellion. During the fighting in Arcada, King Aruthien found Tolwyn's Edge in the ruins of the Temple of Kath, and bore that sword throughout the war with Nagul. It is said that his blade decapitated Nagul at the Plain of Lances.
Aruthien returned home to be declared King by his people. He set about ruling his homeland, doing his best to improve the lot of his folk. Aruthien was depopulated and exhausted for decades of war and occupation - but they were given no rest. For years, armies of Orcs, Goblins, and other creatures boiled southward through the Grimwall Gap and attacked Aruthien's Kingdom. For ten years, the Aruthiens grimly held on, led by their Paladin-King, fighting the Horde as it attacked them every year.
Finally, in 50 TC, Aruthien realized his Kingdom could no longer stop the Horde. Messengers went out to every part of the Kingdoms, asking Aruthien's old allies in the war against Nagul to come and lend their strength to the defense of his Kingdom. Though times were not easy in the other Kingdoms, they sent what they could. Great bronze Ehrenlanders, not seen for decades in the Kingdom, came northward. Dark-skinned Tantathians. Wise Barlozians. Spaarthans on their splendid steeds. Amazons from Sabatia. From all realms came those who would fight for Aruthien. The next spring, the Horde came south again, larger than ever. With the aid of a Sea Elf named Navalus, Aruthien's strengthened armies managed to crush the Horde in the Grimwall Gap in a three-day battle. Moreover, a small band of picked Rangers managed to sneak into Arnland and defeat the Ice Queen herself - the master of all the invading armies.
The Kingdom of Aruthien was safe - though the War of the Crystals was launched. His Kingdom secure, Aruthien was asked by his nobles to wed at once and produce an heir. He chose the daugher of his ally, the sea elf Lysa bel-Navalus. They had three children: Casta, Erian, and Thadus (the Younger).
Aruthien ruled in relative peace for the remainder of his reign. He died in his sleep in 72 TC.