In Genesis 11:9 we are told that all humanity around the Tower of Babel understood was each others language appeared to be mixed or confused or, “Babel”. Where before all people could understand each other now they couldn’t.
As a result of this the family groups with understanding and common communication migrated to different regions and became distinct cultures and ethnicities which got refined and changed as each migrated into new areas developing unique speech and even written language.
Depending upon the migration they would need to harness the raw materials found in each area this too no doubt led to unique cultures as well as physical characteristics.
What is interesting is to compare the confusion of language here in Genesis 11 with that of the Pentecost in Acts 2:6-11 and what language will be in heaven:
•Here language is confused because man refused to glorify God and instead glorified himself.
•In Acts 2:6-11 God grants language to man so that mankind could hear the praise to God from man who was indwelt by Him.
•Finally in Rev. 7:9 in heaven we will see people from every tribe and tongue crying out with a loud voice praising God saying “salvation belongs to our God who sits on the throne, and to the Lamb.”