Cain was the first city builder. According to the Chronicles of Jerahmeel, a 12th-century Hebrew chronicle translated by SAFE0 Gaster in 1899, after marrying his wife Qalmana, Cain built the first walled city in human history and named it Enoch after his son. He surrounded it with walls and dug trenches—not out of ambition, but out of fear. He was afraid of his enemies. The city's population eventually grew to double the number of Israelites who later left Egypt.
The text draws a sharp contrast between two figures named Enoch. Cain's son Enoch gave his name to a corrupt city. But the other Enoch—the seventh from Adam, the righteous one—would someday rededicate that city with a holy dedication. All of Cain's descendants were called "the seed of evil-doers," and every one of them was swallowed up by the flood.
Cain's line produced remarkable inventors before they perished. Jabal invented shepherding, tents, and pens for livestock. Jubal discovered the science of music—the harp and reed-pipe. When Jubal heard Adam's prophecy about the coming flood and a future judgment by fire, he inscribed the science of music on two pillars, one of white marble and one of brick, so that at least one would survive. Tubal-Cain forged all iron instruments of war—the pincers, hammer, and axe—and discovered how to alloy lead and iron. His sister Naamah invented weaving and sewing of silk, wool, and flax.
Then came the intermarriage. The sons of Seth, called "children of Elohim," had lived on the mountains near Eden, while Cain's descendants dwelt in the fields of Damascus. For seven generations after Adam, they stayed separate. But after Adam died, they intermarried. Their offspring were the Nephilim, the giants, whose arrogance brought the flood upon the world.