Father Pedro was born in the Basque area of Spain in the parish of Santa María Ceánuri, near Bilbao, on the road to Vitoria.
He entered the Franciscan novitiate in Bilbao at 17. Seven years later in Aránzazu, he volunteered for the missionary College of San Fernando in Mexico City. He was chunky and full in the face.
Since 1769 he had traveled perhaps 10,000 miles from the north of Spain to Mexico; from there to Baja California; and then, in 1772, when the Dominicans took over, back to Mexico City; in 1774 by transfer to the College of Querétaro and, finally, to Tumacácori where he was there as early as 1775. He served with Father Tomás Eixarch. He was destined to spend the remainder of his life, 45 years, in the desert Pimería.
In May 1775, Father Visitor Antonio Ramos came again to Tumacácori on an inspection tour. Economically things were not too bad. Livestock was in good shape and enough grain and produce were grown to feed the mission. Proceeds from the sale of surplus seed went to clothe the Indians and to furnish the church. The mission business agent had 350 pesos from the sale of provisions to the presidio and settlers in Tubac. That all this was true, Father Eixarch swore at Tumacácori, May 12, 1775.
In August 1775, there was talk of deactivating the presidio at Tubac and transferring the garrison. Captain Hugo O’Conor, commandant-inspector of all the northern frontier, and his staff took stock of the Tubac presidio and their verdict was harsh. O’Conor wanted the presidios of Sonora to fall in a neat line. If he moved Tubac to Tucson and Terrenate to Santa Cruz, they would line up with Fronteras at San Bernardino. A presidio at Tucson would be a perfect closing of the Apache frontier.
Anza was planning the second trek to California. Father Tomás Eixarch was going to the Yumas on the Colorado while Anza was on the trip. Eixarch was gone for seven months. Shortly after he returned, he left Tumacácori.
Father Juan Bautista de Velderrain came to replace Father Tomás late in 1776. By early 1777 he would move on to San Xavier del Bac.
For most of his three years at Tumacácori, the rotund Arriquibar had as compañero Joaquín Antonio Belarde who came as early as September 1777. The two Basques worked together through the spring of 1779. Belarde left first, apparently again for San Xavier.
Arriquibar carried on another ten months and was seemingly overjoyed to leave. When he married an Indian couple March 27, 1780, he wrote the entry with a flourish. Taking up nearly a page, he added in jubilation: “This was my last entry.”
When he left Tumacácori he took the Ramírez family with him. He had grown very close to Interpreter Juan Joseph Ramírez and his wife. At San Ignacio where Arriquibar endured through 1794, he provided for the Ramírez clan. After Juan Joseph died, Arriquibar reared the children. In the Franciscan’s dotage, Teodoro, one of the children, looked after him. Finally, in 1820 when the old Friar died, he left everything he had acquired as a military chaplain to Teodoro, who, for 50 years after, enjoyed rico status in Tucson.
Lista de los cuarenta y nueve religiosos . . . a el colegio de propaganda fide de San Fernando de México, 1769, AGI, Guad., 369. Victor R. Stoner, “Father Pedro Antonio de Arriquibar, Chaplain of the Royal Fort at Tucson,” ed. Dobyns, AW, Vol. 1 (1959), pp. 71-73. Arriquibar made his earliest extant entry at Tumacácori, a baptism, February 26, 1775, and his last entry, a marriage, March 27, 1780. DCB.
 Visita of Tumacácori, May 12, 1775, Libro de patentes, ACQ; Kessell, ed., “Father Eixarch and the Visitation at Tumacácori, May 12, 1775,” The Kiva, Vol. 30 (1965), pp. 77-81. Six weeks earlier a statement of the Sonora missions’ monies for annual expenses showed Tumacácori, still listed as Guevavi, with 580 pesos 5 reales. Átil, San Xavier, and Cocóspera were poorer, San Ignacio more than three times as rich. Razón del estado, March 30, 1775, CC, 201-81.
 Garcés cosigned the site inspection at San Xavier del Bac, August 20, 1775, ibid. Dobyns translated it in Lance, Ho! Containment of the Western Apaches by the Royal Spanish Garrison at Tucson, p. 5. See also Moore and Beene, “Report of O’Conor,” pp. 270-71.
 Arricivita, Lista, 1769. Madoz, Diccionario, Vol. 16, p. 345. Arricivita, Crónica seráfica, p. 560. Lists of personnel, ACQ, M. Font to Ximénez, November 30, 1776, and January 20, 1777. Belarde seemed to take over burials at Tumacácori. A hiatus in the record, where several pages were removed, ends with Belarde’s entry on September 24, 1777. His last entry as Arriquibar’s compañero at Tumacácori, also a burial, was dated May 30, 1779. DCB.
 DCB. Arricivita, Crónica seráfica, p. 560. CSCQ, Difuntos.
 Arriquibar baptized Gabriela Ramírez, March 20, 1776, and José Loreto, December 10, 1778; he buried Juan Crisóstomo, November 17, 1777. DCB. Stoner, “Arriquibar,” p. 77.