Re: Actually...
Actually your view of history is very Eurocentric.
The Monguls and other people of the Steppes--Kubla and Genghis Kahn, Tammerlane developed stirrups. They could stay on their horses and still aim their arrows--something no one else could do.
No justification or ideology was involved. Plunder was just an effective way of making a living and easier than trying to farm.
The N'goro peoples that gave birth to Shaka Zulu suffered from an overpopulation problem of both people and their cattle. One of the largest expansions in history had simple greed as the motivation.
Actually, most war has had pretty pure motivations and not a lot of duplicity.