If Abraham was, then he was born and raised in Sumer of Mesopotamea , this Ur was just  near Uruk.

In the third millennium, when Abraham was said to exist Ur of Sumer was the metropolis of Mesopotamea —it was a port on the Euphrates close to the Persian Gulf. The river bringing rich alluvium down to Ur, creating a floodplain giving generous sustenance to a population of perhaps 12,000 at the city’s peak around 2100 b.c.

Few people outside this area were literate.

If Abraham was literate, that would mean he had taken schooling at the house of a priest or bureaucrat who would have given him a broad knowledge base. He would have studied languages, arithmetic, and accounting, but above all else he would have been immersed in Sumerian literature. This would be the intellectual milieu in which he grew up.

As  child playing with his brothers Haran and Nahor, perhaps a thin teenager of middle height, dressed in comfortable leather and wool?

With the use of our imagination we might see Abraham developing into a tough, solid young man with demonstrative leadership skills. Like the other residents he may have worshiped Sin, the god of the moon and Ur’s chief deity. Religion was Polytheistic so Mesopotamians worshiped a pantheon of deities, including the major ones like  Sin, like every one else Abraham may have had an additional, personal god, each home, a Household god.

Others visualise Abraham, a Man of all Seasons” born to a  Terah, who was the High Priest of the Temple of Ur.

Could it somehow have been, Abraham’s reflections on the moon god that led him to the idea that the world is governed by one God?

Why leave all of this?

The Last of the Sumerians

Within a few centuries the Sumerians had built up a society based in 12 city-states: Kish, Uruk (in the Bible, Erech), Ur, Sippar, Akshak, Larak, Nippur, Adab, Umma, Lagash, Bad-tibira, and Larsa. According to one of the earliest historical documents, the Sumerian King List, eight kings of Sumer reigned before the famous flood. Afterwards various city-states by turns became the temporary seat of power until about 2800 BC, when they were united under the rule of one king–Etana of Kish. After Etana, the city-states vied for domination; this weakened the Sumerians, and they were ripe for conquest–first by Elamites, then by Akkadians.

The Sumerians had never been very warlike, and they had only a citizen army, called to arms in time of danger. In about 2340 BC King Sargon of Akkad conquered them and went on to build an empire that stretched westward to the Mediterranean Sea. The empire, though short-lived, fostered art and literature.

Led by Ur, the Sumerians again spread their rule far westward. During Ur’s supremacy (about 2150 to 2050 BC) Sumerian culture reached its highest development. Shortly thereafter the cities lost their independence forever, and gradually the Sumerians completely disappeared as a people. Their language, however, lived on as the language of culture. Their writing, their business organization, their scientific knowledge, and their mythology and law were spread westward by the Babylonians and Assyrians.

http://history-world.org/sumeria.htm

Terah, as the Patriarch of the family was the decision maker and depending where we situate this family, the extract above is a gloss of something I have read recently,  I think that Terah took his extended family away from Sumer after seeing the writing on the wall.