Complex sentence: Clan Vuirich (Clan MacPherson) and Clan Day (Clan Davidson) were the original co-founders and referred to as "old Clan Chattan", added to these were six "stranger septs" who took protection from the clan.
Split into simpler sentences: Clan Vuirich (Clan MacPherson) and Clan Day (Clan Davidson) were the original co-founders and referred to as "old Clan Chattan". Added to these were six "stranger septs" who took protection from the clan.