How about the sacking of Rome? I would say that it is rare because one preindustrial civilization would not have too much of an extra advantage over the other, whereas an industrialized and advanced civilization could have a clear advantage, especially when it comes to weapons.
earthquakes and civil war
Nope
they wanted to move to another countrycell phones
slavery
Deforestation
The collapse of dictatorships in Latin America
dominant factor
Factors come in pairs. If you know one factor, divide it into the number. The answer will be another factor.
No, that's just a factor. A common factor is when that factor is also a factor of another number.
A factor multiplies with another factor to create a product.
High mountain ranges
they were acomplished diplomats