understandable human fear (associated with any weather occurrence that even hinted to Noah's family, and subsequently their descendants, at a possible replay of the horrific 370-day-crisis of the World Flood) had been specifically taken into account by God's Rainbow Promise of Never–Again for all humanity.

The reminder of this Covenant Promise continues today in the rainbow around the Throne of God (Revelation 4:3) and
it applies to any threat to the survival of the human race (including meteorite collision, or threat of Armageddon).

this natural humanly-defensive-attempt in planning to construct a permanent one-ness/unity, as represented in their tower, rather than spreading out as God had instructed them, was a very understandable act of fearful distrust of the natural world, but it was also by implication so toward their caring Creator.

indefinite period of very slow migration down from the northern highlands lasting at least four generations (Arpachshad to Eber in Abram's genealogy) which had allowed for seasons of planting and harvesting in this process (Genesis 9:20), these descendants of Noah's family now eventually arrive on the flat plain of southern Mesopotamia (Shinar / 'country of two rivers'), most probably near the site of a city that is later in history known as Eridu.

The idea of its top reaching to God's Heaven is not what the Bible says. The term שָׁמַיִם (shâmayim) refers to sky, and it is likely that it was 'according to the heavens' which would simply refer to its twelve stories for the Zodiac (visible Milky-Way constellations), but their united organisational ability is referred to by God in their continuing defensive-reaction from the past trauma of the Global Tsunami as –

to this distrust, language was the necessary target to block their common intention (by communication breakdown) and to therefore further motivate their global dispersion to repopulate the planet.

Eventual Dispersion-Migration Routes:

although the above map assumes a land route in general (such as Beringia across the Bering Strait from Asia/Siberia to America/Alaska), there is increasing evidence of the ancient use the clockwise sea currents of the north Pacific and Atlantic oceans in the peopling of the Americas (as has been shown by historian Gavin Menzies 2013).

to human DNA, language relationships also provide a reflection of the global movements of human populations.
For instance –

The time and place where the migrating group separated into two, which later became the Latin and Sanskrit speakers, is not known.

from these clues that both the Latin and Sanskrit speakers originated from the catastrophic collapse of the Bosphorus wall which caused the Black Sea basin flood about 5,600 BC, for the language of the Latin speaking farmers, who eventually settled as refugees on the flat plain of Latium (Lătĭŭm) beside the Tiber river in Italy, bears no relation to the languages of the Italic hill tribes at that time or to their aptitude in management. The fact that many centuries later God speaks to Israel, concerning their nationalist pride in His bringing them from Egypt, by making reference to the fact that His also brought the Philistines from Caphtor/Crete (of the Minoan civilization), which was caused by the horrific tsunami from the explosion of the volcanic island of Thera (its remains now called Santorini) indicates that God has used natural catastrophes in the past to propel the migrations of peoples.

It may also be of interest to note that the Biblical Hebrew term for Greeks, sons of 'Javan' (Genesis 10:4), is related to the name 'Ionian' for the earliest of the Greeks to settle in Greece.

migrations of people groups has largely been caused by the climate fluctuations arising from natural processes which then causes competition for limited resources, in which the less dominant are forced to migrate.

the unique direct intervention of God to break-up humanity's Babel attempt to consolidate their unity was not in any way punitive, as is explained for us in Acts 17:26-27 through Paul's summary statement to the wise men of Athens –

of the people, to form tribes and nations developing distinct languages and customs, human life-experience had changed forever from its origin in Eden, now with a far greater vulnerability to their environment and a consequently significantly reduced life-span within which to exercise their choices: and its inherent challenge to "feel their way toward Him and find Him" because of this vulnerability.

The natural process in this dispersion migration across the world eventually results in the visible variations among human beings of today. For instance, the oriental eye is actually the same as any other, but its epicanthic fold (the skin fold of the upper eyelid covering the inner angle of the eye) helped protect the eye from the dangerous freezing wind which threatened the eye-sight in their migration route from the Middle East and so those with more of this natural protection became the dominant strain on that route,
and likewise other features of variation in other directions.

this background, God's heart seeks those who trust Him enough to hear Him – and the family of TERAH, a descendant of HEBER, now comes into this focus.

structure of the Genesis text (Gen.10:21-25) Abraham's ancestor Heber/עבר (B5 at the Babel Division in the graph above) is presented as the origin of the people-group called Hebrew, of whom "Abram the Hebrew" is its most famous representative.

This affirms the genealogy's purpose as specifically Abrahamic history, and that it is not a time-measure for general chronological purposes as it has sometimes been unfortunately used.

Also, the common theory that the group designation 'Hebrew' arose from meaning 'other side' as to their migratory origin from 'beyond' the Euphrates (from Ur) is not probable for the following reasons:

this postulated origin of the term is not reasonable.

graph illustrates the radical change to human life conditions illustrated in this family lineage (an average longevity drop of 55% at the Flood, primarily from physical change*) and, subsequently again, an eventual average 50% drop consequent after the Babel division/dispersion of humanity (from psycho-social change).

to the Bible's Genesis record, the changes in average human longevity were directly associated with – 

not the purpose of Abraham's genealogy. This is affirmed by its stylised structure of generations in the Genesis record (10–FLOOD–10). That is, the stylised nature of the Abraham's ancestral genealogy means that the number of generations cannot be used for chronological purposes as it does not necessarily include all generations ('father of...' = ancestor of...).

So, an understandably negative reaction to evolutionary theory of origins should not be allowed to colour our approach to precious Holy Scripture.

New Testament (in Luke) shows us that all our existing Hebrew copies of Genesis have lost one generation from this Genesis genealogy, which has unfortunately helped hide its stylised structure, and it has also lost the age factor of that particular ancestor ('Cainan').

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from the above Babel Division, the eventual diversity of languages, amplified by the continued migrations of people groups, is reflected in the table below for the Indo-European group alone.

FOR A ROUGH TRANSLATION SIMPLY SELECT A LANGUAGE