it an attractive location for Native Americans to camp, hunt, gather and fish. The numerous oak groves along the creek provided an abundant supply of acorns, a staple of their diet. About 70 archaeological sites have been discovered along the creek, with 33 on the northwest side and 47 on the southeast side. An Acjachemen village situated near the confluence of Aliso Creek and Sulphur Creek was named Niguili, possibly meaning "a large spring" in the Luiseño language. The placement of the tribal boundary at Aliso Creek has been disputed, as the usual practice among indigenous peoples of this region was to claim watershed divides rather than stream channels as boundaries. Constance Cameron challenged this view in the paper Aliso Creek: The Great Divide? (1974) presented to the Southern California Academy of Sciences, arguing that the boundary lay north of Aliso Creek and that the entire stream lay within Acjachemen land. D. Earle (1992) further stated that "There is some evidence... that Gabrielino (Tongva) territory may have extended only as far south as the Tustin Plain" (a location about north of Aliso Creek). This contradicts the generally accepted theory originated by Alfred L. Kroeber (1925) who stated that "Juaneño (Acjachemen) place names do not extend north of Aliso Creek". The Master Key (1956) by Bernice Eastman Johnson and The First Angelinos (1996) by W. McCawley also place the boundary at Aliso Creek. Spanish exploration and colonization On July 24, 1769, the Spanish Portolà expedition led by Gaspar de Portolá, traveling north from San Diego, reached a stream which Fray Joan Crespí described as "Alisos Creek", which was actually the Arroyo Trabuco. They camped there for two days before continuing on and crossing what is now known as Aliso Creek, where they found wild grapes and roses in abundance, on July 26. Crespí wrote in his diary, "So we went on over very open country, with hills and broad mesas, ascending and descending through three or four little valleys of good soil well grown with alders." He also wrote of the local Acjachemen people: "They came without arms and with a friendliness unequaled; they made us presents of their poor seeds and we made return with ribbons and gew-gaws." These first explorers were soon followed by Franciscan missionaries who established Mission San Juan Capistrano in 1776 near the main population center of the Acjachemen people, on San Juan Creek about east