What does 'in the days of Peleg the earth was divided' mean in Genesis 10:25?
Four generations after Noah, Peleg was born, the division of people and nations began at the Tower of Babel event in Genesis 11.
The flood occurred around 2349–2348 BC, and Peleg was born in 2247 BC about a hundred years later.
The founding of Babylon was around 2234 BC, or about thirteen years after the birth of Peleg.
The Egyptian state lasted 1663 years, counting backward from the time that Cambyses, king of Persia conquered Egypt in 526 BC, gives us the year of 2188 BC for the founding of Egypt, about 60 years after the birth of Peleg.
About this time Mizraim, the son of Ham, led his colony into Egypt, the Hebrew word for Egypt is Mizraim or the land of Ham. (Psalm 105:23,27)
Greece - Egialeus, king of the Greek city of Sicyon, west of Corinth in Peloponnesus, began his reign in 2089 BC, this king started to reign about 160 years after the birth of Peleg.
Babylon, Egypt, and Greece each spoke a different language. The Tower of Babel would have had to have occurred before the founding of these other kingdoms. Babel (Babylon), being in the same region as the Tower, would have been one of the earliest kingdoms.
Of the other kingdoms, the ones most distant from Babel would have been founded the latest. First Babylon, then Egypt, and then Greece.
After the Tower of Babel, people were forced to split into groups according to their new language.
This is what the reference means “the earth was divided”
25 And unto Eber were born two sons: the name of one was Peleg; for in his days was the earth divided; and his brother's name was Joktan.