Bonilla's Expedition.—About the year 1594, the governor of the province of Nueva Vizcaya commissioned Francisco Leiva Bonilla, a Portuguese explorer and adventurer, to lead an expedition against a predatory tribe of Indians that had for some time been harassing the province. The exact date of the expedition, as well as any definite account of its operations, is not obtainable, for the reason perhaps that it was in a measure contra bando—i. e. illegal. Bonilla started upon his mission, but after he was well out upon the plains he heard rumors of the wealth of Quivira (q. v.) and decided to visit that province. In some way, just how is not clear, the governor learned of this movement and sent a messenger in the person of Pedro de Calorza to recall the expedition. Calorza failed to find Bonilla, who was so unfortunate as to get into a quarrel with his lieutenant, Juan de Humana, in which he lost his life and Humana then assumed command.

Just how far north or east the expedition proceeded is largely a matter of conjecture. Prof. John B. Dunbar is of the opinion that it may have reached central Kansas, and possibly the gold mines of the Black Hills in the western part of South Dakota. After Bonilla's death, and while the expedition was crossing a large river, which Dunbar thinks may have been the Platte, on balsas (rafts), three Mexican Indians took advantage of the opportunity to desert. It was from one of these Indians, Jose or Jusepe by name, that Gov. Onate, of New Mexico, learned of the expedition in 1598.

While Humana and his men were encamped at a place afterward called Matanza they were surrounded by an overwhelming force of the Escanjaque Indians, who set fire to the grass and then rushed upon the camp. Bancroft says that only two people escaped the general slaughter which ensued. These two were Alonzo Sanchez and a mulatto girl, who eventually found their way to New Mexico, where they imparted to the authorities the news of the fate of the expedition. According to an Indian tradition, Humana and his men were exterminated by the Escanjaques as they were returning from the mines of Quivira laden with gold. It may be that this tradition is responsible, in some degree at least, for Dunbar's suggestion that Humana visited the Black Hills region. Bancroft says that Zaldivar found traces of the expedition in the fall of 1598, and closes his account of the event as follows: "When we take into consideration their sources, it is not surprising that the records of Humana's achievements are not very complete."