In post civil war america, who possessed much of the power?

The correct answer to this open question is the following.

Although there are no options attached, we can say the following.

Most anthropologists believe that the migration process of the native Americans across the present-day Bering Strait was completed 15,000 years ago.

Historians and anthropologists agreed that migration through the Berin Strait started approximately 30,000 years ago when the first humans from Asia crossed the Berin Strait that was frozen at that time due to the extremely cold temperatures. They came from Siberia to America by crossing what is formally known as the Berin Land Bridge.