Hebrew years 240 to 360 (3520-3400 BCE)
Enosh would have surely not stayed with his direct parents, Adam and Seth, who feared God. He rather left them to live a life nearer to his uncle Cain.
In year 325, Enosh had a son called Kenan which may have been named so in honour of Cain. The two names are written in a similar fasiohn: קַיִן for Cain and קֵינָן for Kenan. To materialise this similitude in English language, we should write Cain as KaYiN and Kenan as KeYNaN, and not to forget that the voyels have no great importance in Hebrew.
On Cain’s side, Enoch’s successor was Irad, a name derived from the Hebrew root "Ir" which means city. Because the Biblical text states that they built cities and named them after their sons, we can assume that Irad was possibly the one who gave his name to the ancient city of Eridu, in southern Mesopotamia. Some of the sons of Enoch probably returned to the other side of the Fertile Crescent and established their own city in the Negev region, south of Israel. The city was named Arad, probably after Eridu. It was probably the first city having been planned according to a pattern or design: all the houses were similar in shape and arranged in a way to create streets converging to a single place where rain waters were collected in a deep reservoir, made of the two stones found in this region: limestone and flint.
Tel Arad - the water well
The rulers of these city states of Sumeria had to create myths around fear to dominate their people, and they forbade to mention the name of the real and unique God. For this goal, they assumed the role of god-rulers and new pantheons were invented. Idolatry started to spread in the times of Enosh and Enoch.When kingship from heaven was lowered, the kingship was in Eridu. In Eridug, Alulim became king; he ruled for 28800 years. --- Sumerian king list
The name Alulim is very close to the biblical name Elohim, the name of God during the Creation. This proves that the rulers of these ancient cities usurped the name of God for their own designs to rule over their people. This Alulim is assumed to have been the founder of Eridu/Eridug and to have reigned around 3500-3000 BCE. This is very similar to the timeline of the Bible in the times of Irad, the grandson of Cain.
Sumerian list of gods (about 2400 BCE)
Archaeology shows that writing was invented in Sumer, about 3500 BCE (Biblical Year 260). It is likely that the writing greatly helped these god-rulers spread their control over their people, because rules are better imposed once they are committed in writing. Without the invention of writing, their enterprise would have been more limited. At the time, the first writing was based on pictograms, until it evolved into cuneiform writing which had been used for over 3000 years. Cuneiform was later replaced by alphabets (as a combination of letters to form words, and not symbols to represent concepts) as close as we know them today.
 Genesis 4:17
 See sources about the Sumerian King List in Wikipedia