According to the book "Historica de California", their first meeting and treaty was remembered by General Vallejo as taking place in June 1835 on Vallejo's first day arriving into present-day Sonoma County: General Vallejo recounts sailing into Sonoma in 1835, just assigned by the Mexican military to extend Mexican domain in the North Bay to maintain a Mexican stronghold against the Russians at Fort Ross. Vallejo described coming to San Rafael, stopping to form an alliance with a Coast Miwok tribe there, then proceeding past Novato to the rancheria of Captain Pulpula near present-day Schellville where he found over 3,000 curious Native Americans amassed, led by Sem-Yeto. Vallejo pitched tents and dispatched messengers to ask all Native Americans in the region to make treaties with the Mexican government. Vallejo claims that within 48 hours a gathering of 11,000 natives had formed, and only a third of them seemed friendly to him. He remembers Sem-Yeto acted as his interpreter, and remembers how Sem-Yeto urged and harangued the gathering crowds to be friendly to the arriving Mexicans, persuading them that alliance meant Mexican military aid, and suggesting they could better punish enemy tribes. Thus Sem-Yeto not only formed an alliance with the Mexicans, he also gained a following, of many natives in the region in addition to his own tribe, the Suisunes.