Answer: The Monroe Doctrine is the best known U.S. policy toward the Western Hemisphere. Buried in a routine annual message delivered to Congress by President James Monroe in December 1823, the doctrine warns European nations that the United States would not tolerate further colonization or puppet monarchs.
Invasions by Barbarian tribes. ...
Economic troubles and overreliance on slave labor. ...
The rise of the Eastern Empire. ...
The most important reason for the collapse of Rome was the failure to actually integrate what they conquered. When Roman soldiers conquered new lands, it was rare that they ever attempted to force their culture, ideals, or laws upon the natives and barbarians. Thus, when the Empire began suffering internal struggles, the natives they had conquered decided to take action, which lead to the swift collapse by barbarian invasion from all sides. It's hard to pick a LEAST important reason, seeing that there were many of them, but I suppose a contender would most likely be the common refusal of the Empire to even acknowledge that barbarians were rising. On the outer edges of their territory, in places like Gaul and Morocco, the Roman government was reluctant to even recognize the threat of the barbarians, thinking that even accepting that these barbarians were causing trouble would weaken their prestige in the public eye.
In 1937, the Supreme Court ruled that the AAA was unconstitutional, but the basic program was rewritten and again passed into law. Even critics admitted that the AAA and related laws helped revive hope in farm communities.
The PYRAMIDS AND THE GREAT SPHINX rise inexplicably from the desert at Giza, relics of a vanished culture. They dwarf the approaching sprawl of modern Cairo, a city of 16 million. The largest pyramid, built for the Pharaoh Khufu around 2530 B.C. and intended to last an eternity, was until early in the twentieth century the biggest building on the planet. To raise it, laborers moved into position six and a half million tons of stone—some in blocks as large as nine tons—with nothing but wood and rope. During the last 4,500 years, the pyramids have drawn every kind of admiration and interest, ranging in ancient times from religious worship to grave robbery, and, in the modern era, from New-Age claims for healing "pyramid power" to pseudoscientific searches by "fantastic archaeologists" seeking hidden chambers or signs of alien visitations to Earth. As feats of engineering or testaments to the decades-long labor of tens of thousands, they have awed even the most sober observers.