Peleg was born 101 years after The Flood according to the Masoretic Text’s version of Genesis 11, but 401 years after The Flood according to Samaritan Pentateuch version and 531 years after The Flood according to the Septuagint/LXX version.
I consider the Septuagint version the least likely to be the original for a number of reasons. I've talked about my opposition to the Septuagint primacy cultists before. In the case of Genesis 11 the addition of Cainan is obviously Christian copyists forcing him in to reconcile with Luke 3, the numbers given to him being just a copy/past of Salah/Selah’s make that obvious. Cainan’s inclusion isn’t the only difference between the LXX and the Samaritan versions of Genesis 11 but it is the only one relevant to the question of when Peleg was born.
Many make Peleg’s birth year also their year for the division of languages after the Tower of Babel project was stopped because of what Genesis 10:25 says about why Peleg was named Peleg.
“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.”
But the Hebrew word for “divided” used here is palag Strong Number H6385 which is distinct from parad H6504 used in Genesis 10:5 and 32 in reference to the division of languages.
The other use of palag is Job 38:25 which talked about a watercourse being divided. In fact other Hebrew words clearly cognate with palag and Peleg are words translated river or stream like H3688 and H3690. These Hebrew words are likely cognate with the Assyrian Palgu which refers to the dividing up of lands by canals and irrigation systems. An Akkadian city called Phalgu was located at the conjunction of the Eurphates and Chebar rivers.
Classical Greek was influenced by Semitic languages via its iron age contact with Phoenician sea traders, so it may be worth adding that Pelagos is an ancient Greek word for “sea”. Its contrast with Thelassa or Pontos seems to be in part about being enclosed by islands rather than having only one straight connecting it to other seas. But it also looks to me like seas called a Pelagos are generally shallower and not as deep, like they could be places that were once dry land when sea levels were lower.
I think it’s possible there was a slow rising of sea levels during the early Post Flood centuries caused by waters frozen at the icecaps during The Flood slowly melting.
Genesis 10:25 says the Earth was divided while the verses using parad and Genesis 11 are the people being divided. And in Biblical Hebrew eretz didn’t mean a planet but dry land in contrast to the seas and oceans as we see in Genesis 1:10.
There is another interpretation of what kind of division palag refers to here which is that it’s just about borders between being cemented. That and the water level thing could go together.
This makes it highly likely that what happened around when Peleg was born was later than the Tower of Babel incident rather than before. Which is a circumstantial argument for the Samaritan version being more correct then the Masoretic since I think it likely took over a century for there to be enough people to do the Tower of Babel in the first place.
