You need to specify what empire you are referring to if you want to make it possible to answer your question.
Asia, Europe, and Africa
seven contients
The Songhai Interacted with mostly european. Mainly Portuguese and dutch.
Persia, a province of the Median empire, absorbed Media and, with this combined strength, King Cyrus (the Great) set out to take over the Babylonian empire, absorbing it into his growing empire.)
North America and South America are the two contients located in the Western Hemisphere.
Europe
south America and Africa
Asia Europe Africa Antartica ...
Australia and Antarctica.
Only one: Antarctica.
Earthquakes and mountain building.
North America and Asia