Why would john o'sullivan argue that america should continue to expand its territory (amount of land)

estward expansion, the 19th-century movement of settlers into the American West, began with the Louisiana Purchase and was fueled by the ... In 1845, a journalist named John O'Sullivan put a name to the idea that ... should not be permitted in any part of the Mexican territory that the U.S. might acquire.

Explanation:

the first forms of writing came from them in the form of pictographs around 3100 bc.