As an idea, whatever we now recognise as peace predates written history.
It was probably shaped then by human behaviours and experiences that we now call caution, co-operation, kindness, generosity and sharing. For another's insight on that read Alice Roberts' 'Wolf Road'.
The variety of words used now for what we call 'peace' may have had a common origin in primitive sounds such a 'pax'.
Written records suggest that ancient Greek society may have considered peace as the natural condition of a state with productive citizens well-ordered around practical arrangements for governance and justice. Their military force was applied only with the goal of national peace.
In the subsequent era of ambitious Roman expansion the character and understanding of Peace was naturally influenced by the large scale of military might entailed in acquiring and maintaining an Empire. Within that climate though Roman peace was shaped by a legal framework and system that was a powerful custodian of peace alongside their contemporary ideas of individual virtue and self-control, and divine authority symbolised by their goddess Pax.
Diplomacy was well rooted in that ancient era with Peace maintained by Treaties between empires and city-states. Peace may though have been vulnerable to its dependency on the stability and survival of the agreeing leaderships and the reliable maintenance of any agreed payments or other 'tributes'.
Meanwhile, within the wide range of social ideas and traditions understandings about Peace seem to have developed in different ways in many parts of the world. Those developments were in relative isolation in many parts of the ancient world, becoming more widely known only in the centuries since human exploration discovered and could report that the world continues beyond the visible horizon.
Do some features of what's known from about the ancient European accounts of Peace strongly resemble our 21st century experience of Peace; for example in the role of violence and military might, in Peace being kept by force alongside ideas that there is a role too for acknowledged legal, moral and ethical frameworks.
How much and what kind of development has there been in humanity's understanding of Peace?Aren't there some worryingly strong resemblances between the understandings of peace in the ancient world and those in the 19th and 20th centuries before the World Wars and the emergence of modern social sciences?