The Clans didn't all start the same time in this roleplay, instead, they gradually became what they were today after certain events took place. The founders of each Clan, respective to the order of founding are: Athalso, Maroux, and Ruari.
Below is the detailed history of each individual Clan.
ShadeClan was the first Clan to officially founded in the history. Their founder, Athalso, was a local who slowly rose to power over a smaller clowder. Other cats, soon tried to challenge him, but, the tom fought back in honour of his homeland. Athalso overpowered the other tom with his horde of strong cats. The leader, though, offered the loners a place in ShadeClan for he witnessed that they were strong cats and were much alike his own 'warriors'. The Clan was at peace for a few moons before they became alerted to the presence of another ‘Clan’ arose and called themselves NightClan. Their leader, Maroux, challenged Athalso on many occasions for his territory for it was more sheltered from predators and twolegs. However, the ShadeClan leader decided a fight was in order to settle the manner.
In the years to come, the battle would be named the Great War. ShadeClan supposedly won the battle after Athalso snapped Maroux’s neck in the heat of the battle on the Gathering rocks. After that, the Clans became bitter rivals as NightClan sought to exact their revenge for their fallen leader. Athalso passed away in the months following the battle from old age, and he named his grandson, Stagen, as his successor. Stagen was a leader much like his grandfather, only he wasn’t as headstrong and battle-focused as the older cat. According to some, he didn’t last long as the Clan’s leader before his sister succeeded him after fighting him for the rank. His sister, Arbellaine, ruled like her grandfather up until her death where she and the other leaders of the Clans met under the Gathering rocks to create a truce once every full moon. She also introduced the idea of a naming system to be implemented over generations and that idea was taken and was put in place in the following moons when nurseries were full of healthy kittens.
From there, not much else of nobility happened in ShadeClan history. Arbellaine was succeeded by a much younger cat known as Cinderfang, one of the first cats to take to her naming conventions. Cinderfang became Cinderstar after the discovery of their ancestors who called themselves StarClan. Cinderstar herself was succeeded by her youngest daughter named Sootstar.