What geographic feature served as the biggest catalyst for the westward expansion

Does the threat of global warming require international cooperation? why or why not?

Whats the biggest sea in the world?

What statement about charlemagne is not true? a. charlemagne's empire collapsed during his rule b. charlemagne sent missionaries throughout europe c. charlemagne encouraged the arts and education d. charlemagne ruled much of western europe a. charlemagne's empire collapsed during his rule