Because God told Abram to leave his country..
Genesis 12:1-5 And the LORD said to Abram: "Leave your country, your birthplace, and your father's house, and go to the land that I will show you. I will make you a great nation; I will bless you and make your name great; and you shall be a blessing. I will bless those who bless you, and I will curse he who curses you. Through you all the families of the earth shall be blessed." So Abram departed as the LORD had said to him, and Lot went with him. And Abram was seventy-five years old when he departed from Harran. Abram took Sarai his wife and Lot his nephew, and all their possessions that they had acquired, and the people whom they had acquired in Harran, and they departed to go to the land of Canaan, and they came to the land of Canaan.
Abram in faith obeyed God:
Hebrews 11:8 By faith Abraham obeyed when he was called to go out to the place which he would receive as an inheritance. And he went out, not knowing where he was going.
So he would get a good environment
Traditional chronology puts Abraham's journey to Canaan in 1737 BCE.See also the Related Link.More about Abraham
They had to make products to trade for scarce resources -studyisland
Abraham Lincoln was the President of the USA during the Civil War.
Abraham Linclon lead the Civil War.
Abraham had tremendous foresightedness and he lead the civil war because he knew that this sort of war highlights the basic aspirations of the common people as a whole and will lead the battle for independence to victory.
Abraham led his family from the city of Ur to the land of Canaan. Canaan is an ancient region located in the eastern Mediterranean, which encompasses modern-day Israel, Palestine, and parts of Jordan and Lebanon.
You would travel to the Middle East (Iraq) between the Euphrates River and the Tirgis River, and that will lead to the spot that locates Ancient Mespotamia.
The title of ruler, or the one who was chosen to lead governments, was usually a hereditary title, meaning it was passed down from father to son. I hope this answers your question.
Moses
specializations
The main journey of Israelites to Canaan (from Egypt) was led by Moses and concluded by Joshua after Moses' death. Some 400 years earlier, Abraham led a much smaller group from Harran (in Mesopotamia) to Canaan (Genesis ch.12). This group consisted of just a few family members, plus entourage (ibid). See also:Are_Hebrews_Jews_and_Israelites_the_same_people