In 1914, at the outbreak of World War I (WWI), the Australians, who controlled the southern half of New Guinea, took over the German-controlled regions. After the war, Australia gave land grants to veterans and encouraged settlement of the region. Again this altered the local culture, but only a relatively small number of people actually settled the islands and few made their way beyond the coast. These people made almost no impact on the local cultural, although the displacement of the Germans did end that influence, which was quickly changing a number of aspects of the local culture.
With World War II (WWII), the Japanese took over the islands of Bougainville, New Britain, and most of New Guinea in 1941. The land and water battles on and around New Guinea were brutal with many of the locals participating, whether by choice or not. The locals gained great knowledge of western technology and gained a fair number of guns and other arms through these years.
By war's end the Australians and Americans won the battles in New Guinea and pushed the Japanese out. After the war, the region was placed under the protection of Australia, where they remained until independence in 1975.
Under Australian protection little changed in Papua New Guinea. The Australians slowly introduced changes to the political structure and the economic system in the country that, at the time, was still very dependent on agriculture and natural resources.
Since independence Papua New Guinea has struggled with political stability. Numerous politicians have been ousted with no confidence votes and the representative government is extraordinarily divided. This division and these arguments are primarily based on the fact that the country is very divided ethnically as the numerous tribes, languages, and people struggle to see eye to eye.
Issues facing the government have also been vocal in the island Bougainville, in the country's southeast. The people of this island are very different from many people in Papua New Guinea and tend to have more ethnic and linguistic similarities to the people of the nearby Solomon Islands. Bougainville has continuously sought independence, leading to wars and violence on a regular basis.
International relations have also been poor as corruption is rife in Papua New Guinea and this, along with numerous other issues such as human rights issues, have delayed or hurt talks with numerous foreign countries, most noticeably Australia. None-the-less the people of Papua New Guinea seem to move forward with little focus on the outside world (at least in the country's interior). Most of the people living in the mountains maintain their traditional culture and way of life with noticeable changes, such as the end of head hunting and the conversion to Christianity. Those in Port Moresby and along the coast tend to seek a more western economic, political, and social life.