The rivers were banked out and the inundation regulated by means of canals.

All this demanded no little engineering skill; in fact, the creation of Babylonia was the birth of the science of engineering.
Settlements were made in the fertile plain which had thus been won, and which, along with the adjoining desert, was called by the Sumerians the _Edin_, or "Plain." On the southern edge of this plain, and on what was then the coast-line of the Persian Gulf, the town of Eridu was built, which soon became a centre of maritime trade.

Its site is now marked by the mounds of Abu Shahrein or Nowawis, nearly 150 miles from the sea; its foundation, therefore, must go back to about 7500 years, or 5500 B.C.Ur, a little to the north-west, with its temple of the Moon-god, was a colony of Eridu.
In the plain itself many cities were erected, which rose around the temples of the gods.

In the north was Nippur, now Niffer, whose great temple of Mul-lil or El-lil, the Lord of the Ghost-world, was a centre of Babylonian religion for unnumbered centuries.

After the Semitic conquest Mul-lil came to be addressed as Bel or "Lord," and when the rise of Babylon caused the worship of its patron-deity Bel-Merodach to spread throughout the country, the Bel of Nippur became known as the "older Bel." Nippur was watered by the canal Kabaru, the Chebar of Ezekiel, and to the south of it was the city of Lagas, now Tello, where French excavators have brought to light an early seat of Sumerian power.
A little to the west of Lagas was Larsa, the modern Senkereh, famous for its ancient temple of the Sun-god, a few miles to the north-west of which stood Erech, now Warka, dedicated to the Sky-god Anu and his daughter Istar.
Northward of Nippur was Bab-ili or Babylon, "the Gate of God," a Semitic translation of its original Sumerian name, Ka-Dimirra.