Ancient times
Human political organizations began in the form of primitive tribes. Over a period of several thousand years, they advanced into a variety of cultures worldwide. The first governments were theocracies, arising in river valley cultures that grew in places such as Egypt, China, and Mesopotamia. Empires and Monarchies, such as Assyria, Persia, Qin and Han China, Maurya India, Carthage, and Rome formed around Eurasia from 2000 B.C.E. to 500 C.E., with many of those mentioned being supplanted by other empires, or coming to prominence through the conquest of their predecessors. One of the few governments that was not a monarchy or dictatorship was the city-state of Athens in the Greek Peninsula, which while it existed, was a direct democracy.
 Post-classical era
The end of Ancient Times, marked by the fall of the Roman Empire of the Mediterranean Basin in the fifth century C.E., heralded the coming of new empires such as the Islamic Caliphate, Byzantium, and Tang China. In the Americas (both North and South), the Toltec, Aztec, and Incan empires flourished. At the end of this period in the fifteenth century C.E., the kingdoms of Europe, which had been relatively barbaric and primitive through most of this era, went through a renaissance and gained the technological knowledge that would allow them to conquer most of the planet in the next five hundred years.
 Modern times
The dominant power in the sixteenth century C.E. was the Spanish Empire, with its conquest of most of the rich American civilizations, before being surpassed by the British Empire, which became the largest empire in Earth's history pre-UEG. After the First World War, Britain began to rapidly decline as a superpower and the United States rose to prominence. After World War II the two remaining superpowers, the Soviet Union and the United States, plunged themselves into the Cold War with the discovery of nuclear fission bombs and later thermonuclear fusion weapons. In the 1960s the Nuclear Age gave way to the Space Age, with the accomplishments of the superpowers being emulated by Europe, Japan, and eventually the rest of the world. Although the nuclear superpowers signed a treaty to limit their nuclear stockpiles (an event that would eventually lead to the the end of the Cold War), third world countries such as Pakistan and India obtained nuclear weapons technology which led to escalated conflicts between other smaller nations, while political and theological differences lead to the rise of terrorism as an international threat.
 Unified Earth Government
- Main article: Unified Earth Government
The national governments of Earth engaged in several colonial proxy-wars, one of which was the Interplanetary War in the 2100s. Ultimately, the individual national governments on Earth were subsumed by a centralized Earth government known as the Unified Earth Government, which controlled the United Nations Space Command. Many national governments continue to exist under the ultimate authority of the UEG, though their influence and importance has greatly waned. In addition, the individual cultures, languages, and other such unique characteristics live on among the people under the UEG as late as the 26th century.
- ^ Official Halo Wars Community Site: Timeline
- ^ Bungie.net: Halo 3: ODST Field Guide - ODST ("ODSTs are recruited from the Special Operations Groups of all the nations of the Unified Earth Government (UEG)")
- ^ Halo 3, MJOLNIR/C armor description
 See also