Prehistoric warfare
planned campaigns sanctioned by society as opposed to spontaneous massacres) has led to  scholarly debate on the existence of warfare in the narrow sense prior to the development of city states in 20th-century archaeology. In the summary of Heath (2017), accumulating archaeology has made it "increasingly harder" to argue for the absence of organised warfare in Neolithic Europe.
Bioarchaeologists have found from the skeletal remains of more than 2,300 early farmers from 180 sites in northwestern Europe between 8,000 and 4,000 years ago that more than one in ten suffered weapon injuries.
During the period of expansion of hunter-gatherer groups associated with the Pitted Ware culture in southern Scandinavia, the Funnelbeaker farmers constructed a number of defensive palisades, which may mean that the two peoples were in conflict with each other. There is archaeological evidence of high levels of violence among the people of the Pitted Ware culture. 
The 8500-year-old Kennewick Man, a prehistoric Paleoamerican man, and Ötzi, who lived and died in the European Alps some 5,200 years ago, were probably killed in warfare.
Warfare in pre-Columbian North America has served as an important comparandum in the archaeological study of the indirect evidence for warfare in the Neolithic. A notable example is the massacre at the Crow Creek Site in South Dakota (14th century).

Chalcolithic to Bronze Age: The onset of the Chalcolithic (Copper Age) saw the introduction of copper weapons.   Organised warfare between early city states was in existence by the mid-5th millennium BC.  Excavations at Mersin, Anatolia show the presence of fortifications and soldiers' quarters by 4300 BC.
Excavation work undertaken in 2005 and 2006 has shown that Hamoukar was destroyed by warfare by around 3500 BC-—probably the earliest urban warfare attested so far in the archaeological record of the Near East. Continued excavations in 2008 and 2010 expand on that.
Archaeological evidence suggests that Proto-Indo-Iranian-speaking Abashevo society was intensely warlike. Mass graves reveal that inter-tribal battles involved hundreds of warriors of both sides. Warfare appears to have been more frequent in the late Abashevo period, and it was in this turbulent environment in which the Sintashta culture emerged. The spread of spoke-wheeled chariots has been closely associated with early Indo-Iranian migrations. The earliest known chariots have been found in Sintashta culture burial sites, and the culture is considered a strong candidate for the origin of the technology, which spread throughout the Old World and played an important role in ancient warfare. 
Military conquests expanded city states under Egyptian control. Babylonia and later Assyria built empires in Mesopotamia while the Hittite Empire ruled much of Anatolia.
Chariots appear in the 20th century BC, and become central to warfare in the Ancient Near East from the 17th century BC. The Hyksos and Kassite invasions mark the transition to the Late Bronze Age. Ahmose I defeated the Hyksos and re-established Egyptian control of Nubia and Canaan, territories again defended by Ramesses II at the Battle of Kadesh, the greatest chariot battle in history. The raids of the Sea Peoples and the renewed disintegration of Egypt in the Third Intermediate Period marks the end of the Bronze Age.
The Tollense valley battlefield is the oldest evidence of a large scale battle in Europe. More than 4,000 warriors from Central Europe fought in a battle on the site in the 13th century BC.
Mycenaean Greeks (c. 1600 – c. 1100 BC) invested in the development of military infrastructure, while military production and logistics were supervised directly from the palatial centers. The most identifiable piece of Mycenaean armor was the boar's tusk helmet. In general, most features of the later hoplite panoply of classical Greek antiquity, were already known to Mycenaean Greece.

The Late Bronze Age collapse was a time of widespread societal collapse during the 12th century BC, between c. 1200 and 1150. It was sudden, violent, and culturally disruptive for many Bronze Age civilizations, and it brought a sharp economic decline to regional powers, notably ushering in the Greek Dark Ages. Historian Robert Drews argues for the appearance of massed infantry, using newly developed weapons and armour, such as cast rather than forged spearheads and long swords, a revolutionizing cut-and-thrust weapon, and javelins. Such new weaponry, in the hands of large numbers of "running skirmishers", who could swarm and cut down a chariot army, would destabilize states that were based upon the use of chariots by the ruling class. That would precipitate an abrupt social collapse as raiders began to conquer, loot and burn cities.
The Bronze Age in China traverses the protohistoric and historic periods.  Battles utilizing foot and chariot infantry took place regularly between powers in the North China Plain.

Iron Age: Early Iron Age events like the Dorian invasion, Greek colonialism and their interaction with Phoenician and Etruscan forces lie within the prehistoric period. Germanic warrior societies of the Migration period engaged in endemic warfare (see also Thorsberg moor and Illerup Ådal). Anglo-Saxon warfare lies on the edge of historicity, its study relying primarily on archaeology with the help of only fragmentary written accounts.
There are around 3,300 structures that can be classed as hillforts or similar "defended enclosures" within Britain. Hillforts in Britain are known from the Bronze Age, but the great period of hillfort construction was during the British Iron Age, between 700 BC and the Roman conquest of Britain in 43 AD. The reason for the emergence of hillforts in Britain, and their purpose, has been a subject of debate. It has been argued that they could have been military sites constructed in response to invasion from continental Europe, sites built by invaders, or a military reaction to social tensions caused by an increasing population and consequent pressure on agriculture.

Endemic warfare: In warlike cultures, war is often ritualized with a number of taboos and practices that limit the number of casualties and the duration of the conflict. This type of situation is known as endemic warfare. Among tribal societies engaging in endemic warfare, conflict may escalate to actual warfare occasionally for reasons such as conflict over resources or for no readily understandable reason.
Warfare is known to every tribal society, but some societies developed a particular emphasis on the formation of a warrior culture (such as the Nuer of South Sudan, the Māori of New Zealand, the Dugum Dani of Papua, the  Yanomami (dubbed "the Fierce People") of the Amazon.  The culture of inter-tribal warfare has long been present in New Guinea.

See also: Outline of prehistoric technology

Notes: 

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