They could get to know each other without supervision.
and
They had a cheap fast mode of transportation to go to places and to get to school, home and work without the expense of a car.
Russia and Britain both gained partial control of Persia's economy.
"C. was overthrown by invading Mongol tribes in A.D. 1279" would be the best phrase describing China's Song Dynasty, but this was of course not always the case.
I think the answer would be reassure white american settlers that the frontier was safe and peaceful.
Hope this helps
