What were the social organizations during the first global age?

The information box says that the han added 4,000 miles of wall.refer to the mileage scale.how can this be true?

How did the second great awakening affect americans? a revived their patriotismb renewed their religous faithc spread cultural awarenessd increased political activity

What led to the swift population rise over the last two thousand years? check all that apply. increased food supply improved communication improved public health increased birth rates increased resistance to vaccines