sentences:  Some parts of Puebla, Morelos and Hidalgo were also part of Spanish-era Mexico.In 1821, the continental part of New Spain seceded from Spain during the Trienio Liberal, in which Agustin de Iturbide marched triumphantly with his Army of the Three Guarantees (religion, independence, and unity).This was followed by the birth of the short-lived First Mexican Empire that used the "Mexico" name according to the convention used previously by Roman Empire () and the Holy Roman Empire, whereby the capital gives rise to the name of the Empire.