Historians might quibble over the exact details, but by most accounts, there are no periods in history that have been free from war. Much of recorded history has also been filled with imperial or colonial occupations, where a powerful nation uses force to rule over other nations.
In some of the relatively peaceful periods in history, including certain periods under the Roman Empire, and the so-called "long peace" after World War II, the relatively war-free state of politics was due to there being one super-powerful nation that had a particularly strong imperial influence over the rest of the world. If the only reliable way to avoid war is to have global empires ruling by force, then the prospects for any meaningful world peace seem a bit grim.
One thing that needs to be figured out, if we (humankind) are ever going to manage a more peaceful world, is how we can peacefully move on from historical injustices. There's a moral dilemma involved in this. On one hand, if people keep holding grudges, for the wrongs that they or their people have suffered in the past, or for present-day disadvantages that stem from those wrongs, then peace is always going to be tenuous. Real, lasting, stable peace requires trust and solidarity among people. Those things quickly unravel if old grudges are constantly resurfacing.
On the other hand, the moral value of peace seems undermined if, in order to attain peace, we require people to simply ignore or become content with the unjust suffering that has been inflicted on them. This intuition is captured in the slogan "no peace without justice". So, the question is whether we can right historical wrongs and establish the conditions for a future-looking peace, without reigniting the conflicts that surround those wrongs. Different practical approaches to addressing this challenge have been tried, like "truth and reconciliation commissions", and "reparation movements" for historical injustices.
It may be that the hope of world peace hinges in part on people's creativity (and courage) in trying to figure out how to get more communities to buy into these kinds of peace-building endeavours.
(This answer is just part 1 of 2 questions answered, for the follow-up click here "Can there be politics without manipulation?")