Which geographic features protected the roman empire from barbarian invasions until the 4th century A. D

Both pictures below were taken at the same time of day, but one picture was taken in summer, and the other in winter. how can you tell which is in winter

Which of the following situations is an example of an internal migration? a. moving to mexico city, mexico b. moving to san diego, califormia c. moving to toronto, canada d. moving to london, england

Many organizations release indexes used to measure the development of the world's countries. as we learned in this lesson, these indexes measure many factors, from life expectancy to happiness. in your opinion, what are the three most important factors we can use to determine how developed a country might be?