The brief period from 1829 to 1849 was one of the most important in American history. During just two decades, the American government was strengthened, the political system consolidated, and the economy diversified. All the while literature and the arts, the press and philanthropy, urbanization, and religious revivalism sparked other changes. The belief in Manifest Destiny simultaneously caused expansion across the continent and the wretched treatment of the Native Americans, while arguments over slavery slowly tore a rift in the country as sectional divisions grew and a national crisis became almost inevitable.