Arkala
Arkala was the last leader of the Senerii tribe and one of the most powerful leaders of the Spirit Valley Tribes to have ever lived. Commanding a powerful network of matriarchal allies within his tribe, he was able to lead the Senerii to dominate their three larger neighbours through marriage alliances, political intrigue, and military retaliation.
Arkala's reign died with him at the Battle of Four Armies during the War of the Flowers. Initially wishing to join forces with the Fire Nation, miscommunication caused him to perceive war as the only honourable course. Upon engaging Fire Nation forces at the outskirts of the Othii capital, he led the Senerii forces very close to destroying the entire Fire Nation army by cutting off their avenue of retreat. This was prevented by the timely intervention of forces from Even Newer Mexico, led by Bigby Branson. Arkala's forces were surrounded and negotiations to surrender began.
Arkala offered the Fire Nation the Senerii's vassalage and for them to rescind their theoretical declaration of war on the Kaerii in exchange for being allowed to withdraw with his army intact and the Church of Fire to be barred from proselytizing in his lands. The Firelord countered, offering three options: resettlement in other tribe's lands and conversion; leaving their lands to never return; or death. Arkala, recognising that his leadership was only preserved in the latter case, opted for the final choice. Battle resumed and the Senerii army, and the tribe as a whole, were wiped out permanently.