How do scientists estimate when humans reached a new area?

Leah deposited $50,000 in the bank. three years later, she borrowed $40,000 for a new truck. from this description, which is the most accurate statement?

In what is known as the great migration, large numbers of african americans moved from the rural south to northern cities, beginning in the early twentieth century. what motivated this large-scale movement?

What phrase best describes the new worlf order