This fourth beast—the one that struck the most terror in Daniel's heart—is described as devouring the whole earth, trampling it, and breaking it into pieces. The Aramaic phrase translated as "the whole earth" is comprised of two words: kol (Strong's #3606) and 'ara' (Strong's #772). Considering the basic meaning of these two Aramaic words, "the whole earth" is a correct literal translation. However, this same word-combination appears in a number of other places, and it does not consistently mean the entirety of the globe or even the entirety of the civilized world.
We can see this in Daniel's explanation of Nebuchadnezzar's dream: "But after you shall arise another kingdom inferior to yours; then another, a third kingdom of bronze, which shall rule over all the earth" (Daniel 2:39, emphasis ours throughout). We understand this third kingdom to be the empire of Greece under Alexander the Great. His empire stretched from the Ionian Sea to the Himalayas, and included Anatolia, Syria, Phoenicia, Judea, Egypt, and Mesopotamia. Some would say that Alexander conquered the "known world," but this is a misnomer. Every part of the world is known to those living in it, and there were peoples living in essentially every part of the world at this time.
During Alexander's time, substantial civilizations existed in the rest of Europe, and in particular, the descendants of Israel had settled there. Unconquered tribes lived throughout Africa, Arabia, Tibet, Mongolia, not to mention the civilizations in the Americas—all were completely untroubled by Alexander. Also, ancient cultures inhabited India, the South Pacific, and the Far East. The third kingdom in Nebuchadnezzar's vision encompassed the Middle East and the Near East, but it did not rule over "all the earth," as most English-speakers would interpret the phrase. It was a "world-ruling" kingdom only for a specifically defined "world."
Therefore, if we are on the lookout for a kingdom that can devour "the whole earth," we have to understand that the scope of that Aramaic phrase can be significantly limited, and in most cases, it is. This phrase is also found in Daniel 4:1, 11, 20, where it describes the scope of Nebuchadnezzar's kingdom (which was also not truly global), and in Daniel 6:25, where King Darius writes "to all peoples, nations, and languages that dwell in all the earth"—yet Darius did not have a global audience.
The one place where the phrase "the whole earth" actually does imply the entire planet is Daniel 2:35, where "the stone that struck the image became a great mountain and filled the whole earth." This great mountain represents Jesus Christ's rule on earth, which will certainly be a world-ruling Kingdom in the fullest and truest sense of the word (see Revelation 11:15).