"The Caorrani people are an ancient group of clans hailing from the forests to the north of the continent. Long divided and wandering, they have recently joined together for the purpose of establishing a shared homeland. Thanks to Caorrani Clans such as the Bardach, Cousland, Quelius and Rivacheg, today we have a unified Kingdom to call our own." - Excerpt from Caorrani History, Legends and Mythology, by Court Historian Aldous
The outpost of Àirde was originally controlled by a lesser Caorrani clan, even before the unification of Caorran. They were loyal to the Lord of Deargailbh as vassals. However, during a great battle, the Lord of Àirde, being heirless, was treacherously slain by his own wife who then took her own life, thus extinguishing the bloodline. In the absence of a rightful heir, Ewan Cousland, the captain of Àirde's guard, seized the lands and title. Although this claim was not recognized until much later.
Lord Ewan Cousland declared their independence from Deargailbh and fought a war for 50 years. Lord Ewan died in battle, and his son Owen Cousland continued to fight for independence until his death. Though, it was Ewan's grandson, Brian Cousland, that ended the war in victory and Àirde was recognized as a new independent realm. They also gained possession of half of the land that once belonged to southeastern Deargailbh.
After the unification of Caorran under the banner of King Eoghan I, Lord Cailean the Undying was allowed to officialize House Cousland as a cadet branch of House Bardach as a reward for the Couslands aid and loyalty in securing a unified realm for the Caorrani people.
Around the same time, Cailean's younger brother, Lachlann Cousland, took control of Deargailbh with the help of The Bright Custodians, and pledged his loyalty. This led to the creation of a united subrealm called Gallaran. In recognition for his loyalty, Lachlann was given the title of Baron and became the First Custodian of the newly formalized Knightly Order.
Under Cailean's leadership, Gallaran expanded its territory to the West and to the North. He also annexed the insular territories to the South through diplomatic means, gaining new lands with valuable resources. This made Gallaran one of the strongest subrealms of Caorran, and House Cousland as one of the most influential Clans of the Kingdom.
As the Duke of the largest subrealm, Cailean served for years as Chancellor of the Kingdom, and was awarded the hand of Princess Margaret Bardach in marriage by King Eoghan, which resulted in an heir for the Duchy and a claimant to the throne: Aodhàn the Unbound.
Following the sudden slumbering of King Eoghan and his House, Cailean inherited the crown via his marriage with the Princess, and was seen as a legitimate ruler, with the throne eventually going back to King Eoghan's grandson on his death.
On 37-26-3, King Cailean converted his family to the Aeternum Solis, and as ruler he oversaw the mass conversion of the Caorrani people. The aforementioned Custodians became a Holy Order under the Ecclesia by suggestion of the Solar Ecclesiarch Helia I, serving as their Honor Guard, and answering directly to her.
First Custodian Lachlann then gave his lands to the Order, turning The Caorrani Custodians into the first Chapter to have its own lands, able to collect taxes and raise levies. The Custodians's Chapters, despite being a Holy Order under the Ecclesia, are considered vassals of their local realm, and owe their loyalty to their secular suzerain, pledged to defend his or her lands as any other regular vassal would. The Custodians are strictly forbidden to rebel or fight against their lieges, the only exception being in cases of heresy.
Furthermore, King Cailean's grand-niece, Rhiannon Cousland, took the role of Cardinal for the Caorrani Kingdom under the Ecclesia. This places the Couslands as one of the most influential families of the continent, simultaneously holding the leadership of a Kingdom, Holy Order and Cardinalship.