Buddhist nuns from Tibet, Nepal, Bhutan and India made an arduous 4,000 km (2,485) journey on 17 September, from Kathmandu to Leh in India, crossing the Himalayas. They were raising awareness about human trafficking of girls and women in Nepal and India.

"When we were doing relief work in Nepal after the earthquakes last year, we heard how girls from poor families were being sold because their parents could not afford to keep them anymore," 22-year-old nun Jigme Konchok Lhamo told Reuters.

"We wanted to do something to change this attitude that girls are less than boys and that it's okay to sell them," she said, adding that their bike trek shows "women have power and strength like men".

This is the fourth journey the nuns from the Drukpa Order have made, talking to government officials they meet along the way to impart their message of peace, environmental issues and gender equality.

Carrie Lee, president of Live to Love International, a charity which works with the Drukpa nuns says Gyalwang Drukpa, head of the Buddhist order encourages these activities.

"Traditionally Buddhist nuns are treated very differently from monks. They cook and clean and are not allowed to exercise. But his Holiness thought this was nonsense and decided to buck the trend.

"Among other things, he gave them leadership roles and even introduced kung fu classes for the nuns after they faced harassment and violence from the general public who were disturbed by the growing shift of power dynamics," she told Reuters.

Changing attitudes is at the heart of the nuns' movement. "Most of the people, when they see us on our bikes, think we are boys," said 18-year-old nun Jigme Wangchuk Lhamo.

"Then they get shocked when we stop and tell them that not only are we girls, but we are also Buddhist nuns," she said. "I think this helps change their attitudes about women and maybe value them as equals."

South Asia is one of the biggest areas for human trafficking in the world. Since two earthquakes struck Nepal in April and May 2015, more than 40,000 children lost their parents, according to Nepali officials. In these post-disaster situations, trafficking has increased with gangs coercing homeless villagers into bonded labour, with young girls and women are sold into brothels.