Complex sentence: La Sierra Academy was founded in 1922 as a secondary school on land that was formerly part of the 1846 Mexican land grant, Rancho La Sierra from which it acquired its name.
Split into simpler sentences: La Sierra Academy was founded in 1922 as a secondary school. The land on which LSA was founded was formerly part of the 1846 Mexican land grant, Rancho La Sierra from which it acquired its name.