Yellow Bird (Walla Walla leader)

Piupiumaksmaks (alternatively spelt Peo-peo-mox-mox or Peopeomoxmox) meaning Yellow Serpent or Yellow Bird (1800 – 1855) was head chief of the Walla Walla tribe.

While residing at Fort Hall, Jason Lee was greeted by Piupiumaksmaks who presented the missionary with two horses after a test of his medical skills. Yellow Serpent later brought his eldest son, Toayahnu, to be educated at the Methodist Mission, who was christened after Elijah Hedding.

Late in 1844 Yellow Serpent organised the first Walla Walla expedition, with around 40 Walla Walla, Nez Perce and Cayuse men in addition to their families, reached New Helvetia to trade for cattle. After capturing horses that had been previously stolen an altercation arose with one of Sutter's employees, ending with the death of Toayahnu.

Isaac Stevens met Piupiumaksmaks while headed east to chart a path for a Pacific railway in 1853, finding the chief to have a "dignified manner". Piupiumaksmaks then owned "over 2,000 horses, besides many cattle" and maintained a farm outside Fort Nez Percés.

Despite fears by Sacramento settlers of an invasion force of a thousand Walla Wallas in early 1846, Piupiumaksmaks returned with only 40 warriors and declared peaceable intentions. While discussing with Joseph Warren Revere, who was engaged commanding volunteers at New Helvetia, Yellow Serpent stated: "I have come from the forests of Oregon with no hostile intentions... We have come to hunt the beasts of the field, and also to trade our horses for cattle; for my people require cattle, which are not so abundant in Oregon as in California. I have come, too, according to the custom of our tribes, to visit the grave of my poor son, Elijah, who was murdered by a white man. But I have not traveled thus far only to mourn. I demand justice!" The returning party contained those infected with measles, which eventually began to spread across the Columbia Plateau. The outbreak of the disease amongst the Cayuse was a major contributory factor that led to the Whitman Massacre.

Piupiumaksmaks was present during the 1855 treaty council of the Yakima War period. As the war commenced, Piupiumaksmaks had his village near the mouth of the Touchet River. With the advance of an American military unit, he presented himself as a hostage and insisted an end to the conflict. The nearby encamped Walla Wallas began awaiting for the appearance of Head Chief of the Cayuse Five Crows, brother-in-law of Piupiumaksmaks and maternal half-brother of Tuekakas (Old Chief Joseph) of the Nez Perce, before determining to pitch a battle or not. In a meeting with one of his sons the next morning, Yellow Serpent advised that a peaceful route be taken. During the first day of the Battle of Walla Walla, on December 7, Piupiumaksmaks was killed by the Oregon Volunteers who were holding him. Soon afterwards he was decapitated and scalped by one of the Volunteers.