September 13th marks the Battle of Chapultepec Castle where American forces defeated teenage Mexican heroes known as the "Ninos Heroes". On September 16th, Mexicans celebrate independence from Spanish rule with El Grito. Indigenous people originally inhabited Mexico and created great civilizations. The Mexican Revolution from 1910 to 1920 transformed from a revolt against the established order into a civil war, producing a new constitution in 1917 and establishing the National Revolutionary Party in 1929 which ruled as the PRI until 2000.