The Shaman caste is the whole of the Charr Shamans of the Charr legions and is the current leaders of the Charr, headed by Hierophant Burntsoul. They have forced the other Charr to bow to them and rule over them with an iron fist, using their fiery gods and the promise of more power to maintain control over the four High Legions.
The origins of the Shaman caste are unknown; knowledge of their existance intertwines with knowledge of the Titans and the Burnt Warband. Approximately two hundred years ago, the Burnt Warband, seeking gods for the Charr to follow, discovered a Titan (presumably Saevio Proelium, the only known Titan to be on Tyria and was captured by the Order of Whispers around this time) in the volcano Hrangmer. Taking this creature and his brethren to be the gods they sought, they returned him to the rest of the High Legions.
The first known recording of the Shaman caste in history begins here; the Shaman caste of the Flame Legion was, appropriately, the first to worship the titans as gods. Eventually, other Shaman castes from other High Legions took up the worship.
When Bathea Havocbringer refused to worship the new "gods", the Shamans had her executed and as punishment prevented all female Charr from fighting in combat.
For over 200 years, the Flame Legion ruled over the other legions; within the legions, the Shaman caste ruled similarly over the other Charr. When the Flameseeker Prophecies came to pass, their Titan gods were defeated by humans, heralding the end of the Shaman caste's rule. With the Titan downfall, their stranglehold on the rest of the Charr was weakened and various Charr, such as Pyre Fierceshot, began to rebel against the Shaman caste. To regain some of their power, they tried to force a new set of "gods," the Destroyers, upon their race. This failed quickly, as the Destroyers attacked all life, including the Charr. Hierophant Burntsoul was killed by Pyre's warband and humans of the Ebon Vanguard. Pyre and his warband then began a rebellion against the Shamans.