Before the flood, the ancient world had become fully corrupt, with the exception of Noah, who alone found favor with the Lord. He and his family were the only ones spared from the destruction which wiped out every living thing.
About 100 years after the flood, a man named Peleg was born. He was named Peleg, because “in his days the earth was divided,” 1 Chronicles 1:19. Following is the narrative of this division of the earth, found in Genesis 11:1-9,
“Now the whole earth had one language and one speech. And it came to pass, as they journeyed from the east, that they found a plain in the land of Shinar, and they dwelt there. Then they said to one another, ‘Come, let us make bricks and bake them thoroughly.’ They had brick for stone, and they had asphalt for mortar. And they said, ‘Come, let us build ourselves a city, and a tower whose top is in the heavens; let us make a name for ourselves, lest we be scattered abroad over the face of the whole earth.’
“But the Lord came down to see the city and the tower which the sons of men had built. And the Lord said, ‘Indeed the people are one and they all have one language, and this is what they begin to do; now nothing that they propose to do will be withheld from them. Come, let Us go down and there confuse their language, that they may not understand one another's speech.’ So the Lord scattered them abroad from there over the face of all the earth, and they ceased building the city. Therefore its name is called Babel, because there the Lord confused the language of all the earth; and from there the Lord scattered them abroad over the face of all the earth.”
Only 100 years after the flood, a time when Noah and Shem were still living, and there can be no doubt the men who were then living knew that the destruction of the flood had been due to the wickedness of man. But they did not seek after the favor of God, but rather, “(L)et us make a name for ourselves, lest we be scattered abroad over the face of the whole earth.”
So why did He scatter them, and confuse their languages? “(N)othing that they propose to do will be withheld from them.” Mankind before the flood had become altogether corrupt. Now, after the flood, their wickedness would have grown just as complete, for they would have been able to accomplish whatever it was that they set out to do, and we have the example of what it is that they did. The accomplishments they would have achieved would have been in wickedness, just as the tower, and just as before the flood. So He split them up, so that they wouldn’t be able to.
As a part of forest management, men cut fire breaks, in order to control the outbreak and spread of fire, should it occur. When fire breaks out in one location, and begins to spread, the fire break (basically a road cut through the trees) is a gap where there is no fuel available, stopping the fire from spreading further.
In essence, by confusing the languages of man, He slowed down the ability for evil to spread faster, for, “He made from one man every nation of mankind to live on all the face of the earth, having determined their appointed times and the boundaries of their habitation, that they would seek God, if perhaps they might grope for Him and find Him, though He is not far from each one of us,” Acts 17:26-27. One nation of men may become fully corrupt, without impeding another nation from still seeking after the Lord.
This same pattern can be seen in the management of the church; each congregation has autonomy, answering to the Lord alone. If one congregation becomes corrupted, it is much harder for the corruption to spread to another congregation, than if they were all part of the same hierarchy. The great example we have of this is the Catholic church; under the rule of one man, they all follow the same rule, and they all become corrupt together.
Now when He did separate the nations, He planned for the nation of Israel, which He had not yet brought into existence (being many years yet in the future). For Deuteronomy 32:8-9 says,
"When the Most High gave the nations their inheritance, when He separated the sons of man, He set the boundaries of the peoples according to the number of the sons of Israel. For the LORD'S portion is His people; Jacob is the allotment of His inheritance.”
This preparation was done, in that the nations He allotted to the land of Canaan, these would fill up their sin, of their own accord, so that when the time came for Israel to take possession of the land, these nations had reached their peak of corruption, and were therefore rightly removed (remember the curse on Canaan, Genesis 9:25. But even so, He would not remove them before their time, for He says to Abraham when showing him the land Israel would inhabit, “Then in the fourth generation they will return here, for the iniquity of the Amorite is not yet complete,” Genesis 15:16). He prepares all things ahead of time, according to His purpose.
It’s interesting; man is now nearly able to fully work together globally, with the spread of the internet, computers, and translation tools.