HP. Hoodedcobra666 said:
Because...Life. War is in itself, not bad, provided it's not a war between the same species, the same people, a civil war, or amongst people of the same race. Then it's a calamity.
The lamentations of the ancient Philosophers were largely around this, so long nonspiritual people hold control of the earth, there will always be ceaseless war, for the most superficial reasons.
War is a phenomenon of life, species do wage war, and war is frequent. However, if humans become more spiritual, a lot of useless suffering can be avoided.
Alexander mended the ties and evened out of this situation of incessant war, primarily because, he was enlightened. After this, the lesser people took power again, and the situation continued.
Nations do wars over a lot of reasons, and our planet has been in perpetual warfare, even stupid warfare, a lot due to spiritual downfall, rather than actual material problems. Back then, a lot of it was also material problems, such as lack in certain things or elements, which facilitated war very frequently.