Early habitation dates back to approximately 60,000 years ago with the development of small rural societies at that time. Upon contact with Europeans, the indigenous peoples had developed a complex agricultural civilisation based on bone, wood and stone.

The first visitors were the Spanish in 1545, followed later by the Germans, who took formal possession of the northern part of the eastern half of the main island while Britain took control of the southern half. During World War I, Australian troops took control of the whole eastern half and continued administering this territory until the Japanese invasion in 1941. Bitter fighting in PNG resulted in over 100,000 deaths in the warring parties.

Following World War II, Australia continued to administer PNG as part of an international trusteeship system. The creation of a judiciary, public service and legislature gradually took place with preparation towards independence, which was eventually granted in 1975.

The recent era is marked by political unrest and allegations of corruption. An uprising on the island of Bougainville in 2002 saw Australia provide large numbers of police to quell the gang violence that had ensued. While this measure was successful, after a year it was ruled by PNG that this peace keeping police force was unconstitutional and, as a result, Australia withdrew the policing mission. Relations with Australia have been strained by this incident, but PNG is still a large recipient of aid from Australia.