Chinese special policemen rank in a line of battle during an anti-terror drill at a training base of Chengdu Armed Police Headquarters on September 28, 2005 in Chengdu of Sichuan Province, China. (Photo by China Photos/Getty Images)

A Munduruku Indian child is pictured at the Planalto Palace, where a meeting with Minister of the General Secretariat of the Presidency of Brazil Gilberto Carvalho was being held with other Munduruku Indians, in Brasilia, June 4, 2013. President Dilma Rousseff's government sought on Tuesday to defuse mounting conflicts with indigenous groups over its decision to stop setting aside farm land for Indians and plans to build more hydroelectric dams in the Amazon. The government flew 144 Munduruku Indians to Brasilia for talks to end a week-long occupation of the controversial Belo Monte dam on the Xingu river, a huge project aimed at feeding Brazil's fast-growing demand for electricity. (Photo by Ueslei Marcelino/Reuters)

“Kids of Sapa”. Four little beautiful Hmong girls from Lao Chai Village, near Sapa, Vietnam. (Photo and caption by Felipe Hanower/National Geographic Traveler Photo Contest)

In this Wednesday, November 15, 2012 file photo, a young girl in her colorful dress reaches out to greet a Pakistani policeman securing the road outside Kainat Riaz's home in Mingora, Swat Valley, Pakistan. (Photo by Anja Niedringhaus/AP Photo)

The 26th annual National Geographic Traveler Photo Contest is now accepting submissions. Official categories include: “Travel Portraits”, “Outdoor Scenes”, “Sense of Place” and “Spontaneous Moments”. The contest is accepting entries until June 30. Photo: “Forest lights”. Aurora Borealis over the forest of the Pyhae Luosto National Park, Finland. (Photo and caption by Nicholas Roemmelt/National Geographic Traveler Photo Contest)

Two models sit in an acrylic “ZF-Car” from the German manufacturer of the same name at the Automechanika automotive service industry trade fair in Frankfurt am Main, Germany, 12 September 2016. The Automechanika Fair runs from 13 to 17 September 2016. (Photo by Boris Rössler/EPA)

A soldier from the South Korean army special forces breaks stone plates with her head during a martial arts demonstration for Memorial Day at Korea War Memorial Museum in Seoul, South Korea, Monday, June 6, 2016.(Photo by Ahn Young-joon/AP Photo)

A Pakistani farmer guides his bulls as he competes in a traditional bull race in Khunda village in the northwestern district of Attock, some 80 kilometers from Islamabad on January 3, 2015. Tens of thousands of people gather whenever there is a bull race held in Pakistan which are usually the highlight of festivals organized in rural areas of the Asian country, and attract lots of spectators due to their thrilling nature. The traditional competition attracts landlords and farmers from all around the province where the race is held, and they all bring their fastest and strongest bulls in hopes of gaining a reputation. (Photo by Aamir Qureshi/AFP Photo)