The name comes from Greek: Mesopotamia means "the land between the rivers", the Tigris and the Euphrates. Both rise in the mountains of eastern Turkey and run southeast for more than a thousand miles before they meet near the Persian Gulf. Most of this land lies in modern Iraq, with edges in Syria, Turkey and Iran. Here, between about 3500 and 500 BCE, people built some of the first cities, created one of the first writing systems, wrote the oldest surviving collections of laws and ran some of the first empires.

Two rivers, two regions

Mesopotamia was really two landscapes. In the north, the region later called Assyria, winter rains were usually enough for wheat and barley. In the north, enough rain fell to grow grain without canals, so farming villages spread across rolling plains. The south, later called Sumer and Akkad and later still Babylonia, was a flat plain of river silt where summers were fierce and rain rarely topped a few inches a year. Farming in the south depended on irrigation because too little rain fell to grow crops. Farmers dug canals to lead river water onto their fields. The rivers made this possible but also dangerous. They flooded in spring, when snow melted in the mountains, which was the wrong season for most crops, and they could shift their beds and leave a town stranded far from water.

A land short of everything but mud

The southern plain was rich in some things: barley, date palms, fish, sheep, reeds from the marshes and endless clay. It was poor in others. The south lacked stone, timber and metal ores, so its people had to trade for them. Copper came from Oman and Anatolia, tin from as far away as Afghanistan, cedar from the mountains of Lebanon, and the deep blue stone lapis lazuli from northeastern Afghanistan.

The soil carried a slow danger. River water holds small amounts of dissolved salt, and in a hot climate the water evaporates and leaves the salt behind. Over centuries, irrigation caused salt to build up in the fields. In a well known 1958 study, Thorkild Jacobsen and Robert Adams argued that southern farmers gradually shifted from wheat to barley, which tolerates salt better, and that falling harvests weakened the old Sumerian cities. Later scholars have questioned how strong that evidence is, but salty soil remains a real problem for farmers in Iraq today.

Before cities: the Ubaid world

Farming villages appeared in northern Mesopotamia by about 7000 BCE, in cultures that archaeologists name after the sites where they were first found, such as Hassuna, Samarra and Halaf. In the south, settled life took firm hold in what is called the Ubaid period, roughly 6500 to 3800 BCE. In the Ubaid period, villages and temples spread across the southern plain. Ubaid people made a distinctive pottery painted in dark designs, drained marshland, dug small canals and built shrines on raised platforms.

How we know: tells, tablets and dates

Mud brick does not last. When a house fell down, people leveled the rubble and built on top of it. Over thousands of years this turned towns into hills. A tell is a mound built up from layers of old settlements, and Iraq is dotted with them.

Clay brings a second gift. Mesopotamians wrote on clay tablets, and dried or baked clay survives far better than papyrus or parchment. Hundreds of thousands of tablets sit in museums today, and many have never been fully read. They include letters, receipts, contracts, school exercises, prayers, omens and poems, which let historians see daily life in rare detail. The record is uneven, though. It favors cities over villages and herders, palaces and temples over ordinary homes, and men over women.

Dating is harder than it looks. Scribes kept lists of kings and years, but the lists have gaps and overlaps. Dates before about 1500 BCE are uncertain because scholars still debate how to anchor the king lists to fixed points such as records of the planet Venus or of eclipses. Most books, including this course, use the so-called middle chronology. Treat any early date as approximate, often by decades.

Worked example: Reading the mound at Eridu

Later Mesopotamians believed that Eridu, near the ancient shore of the Gulf, was the first city on earth, the place where kingship first came down from heaven. Between 1946 and 1949 the Iraqi archaeologist Fuad Safar and the British archaeologist Seton Lloyd dug into the mound there. Beneath a later temple platform they found a sequence of about eighteen temples, each built on the remains of the one before. The lowest was a small mud-brick room only a few meters across, with a niche and an offering table. Each rebuilding was larger, until the later temples stood on platforms with buttressed walls and many rooms.

The mound tells two stories at once. People kept building sacred places on the same spot for well over a thousand years, which points to strong continuity of belief. And the later legend of Eridu as the first city, while not literal history, preserved a real memory that the far south was where Mesopotamian civilization took shape.