The flat was named (but misspelled) for Don Pedro Sainsevain, who with his brother bought part of Rancho Cucamonga in 1865 and set out a large vineyard. He moved to Cucamonga in 1870 and ran the vineyard and winery with Joseph S. Garcia. In 1874 the Sainsevain brothers purchased land in Hawker Canyon four miles east of Etiwanda and built a large stone house and a reservoir there.[4]
^According to the Los Angeles Tri Weekly News: On Sept. 14 1865 the sheriff with a posse of three soldiers and two or three citizens ran across Henry sound asleep near San Jacinto Canyon, 25 miles from town and killed him after he made some resistance wounding one man. Secrest, California Bad Men p.144-146