In a Land not so very far away, but in a much distant time...
"UHG UNGOWA"
"ME EEGOR"
"I AM STRONG AND BRAVE"
"ME LEAD YOU AND SAY WHAT ARE THE RULES"
"UHG BOOGAHOOGAH"
"ME KRAG"
"ME STRONG AND BRAVE TOO"
"ME MAKE NEW RULE"
"ALL THAT LIKE MY RULES COME WITH ME"
Eegor: "WE HAVE PROBLEM, KRAG TAKING WOOLLY MAMMOTH FROM GREAT PLANES, DRINKING WATER FOM OUR SPRINGS, LESS FOR US, WE MUST DO SOMETHING."
Eegor sends a representative to go out and speak with Krag on behalf of the Eegor Clan. This representative is promptly slaughtered and eaten before any talks ever happen. Eegor is mad. Eegor gathers his men, arms them with rocks sticks and bones, and attacks the Krag Clan. Blood is spilled and many die. In the end Eegor drives Krag and his people out of the land and all is well. Krag leaves, but is not happy. Krag vows to one day return for revenge, and to gain control over the prime mammoth hunting grounds and fresh water springs.
Consequently, as the Eegor Clan grows it must expand its hunting territory and will soon, once again, encounter the Krag Clan. War shall come again.
These experiences are lessons that will be passed down from generation to generation. The Eegor and Krag feud will continue on for a long time. Other clans may split off from either clan and also have conflict, or take allies with any clan. It will never end.
What you have just read is crazy and stupid sounding. But it is also probable that what you've read was similar to what may have happened in real life a long long time ago as the first wars of man were waged.
You have what I want or I have what you want. It's the basis to all wars. How can anyone believe there can be human life without conflict?
The human race grow exponentially. We must reside on land, and we must consume resources. Both of which are not infinite.
War will worsen with time. There will come a time when there is not enough of what we want and need to go around. In some instances that time may already be upon us, or fast approaching.
We are humans, we are destructive and selfish.
Be a realist, or hide your head in the sand and live in fantasy land.
Fact: All these neutral nations that don't war, or are passive and keep to themselves, when the power nations run out of what they want and need, and your nation has some, the power nations will come and take it. Sorry, I speak the truth.
Cruel world, eh?