Les than two decades later, the arrival of the civil war in their corner of the Amazon Basin has forced more than half of the Nukak community of some 500 to flee their ancestral lands. The last big exodus came in April, when 77 Nukak sought sanctuary in the town of San José de Guaviare. Their situation is dire: they cannot return to their lands, but their culture will disappear if they stay put.

On World Indigenous Day, UNHCR highlights their plight – and that of almost all of Colombia's 80 indigenous groups – with a call on the country's rival armed groups to leave threatened people like the Nukak and the Awá out of their fight. The refugee agency warned on Wednesday that the conflict threatened the culture and very existence of Colombia's indigenous people. 

"We have warned repeatedly that indigenous groups in Colombia are at risk of violence and even of extinction amid the ongoing conflict. This is a tragedy not only for them but for the whole of humanity" said Roberto Meier, UNHCR's representative in Colombia.

Together they make up about one million people, or less than 3 percent of the country's population. The conflict causes suffering to hundreds of thousands of Colombians, but the indigenous people have been particularly hard hit.

Some 23,000 of them were forced to flee their homes last year, according to the National Indigenous Organisation of Colombia, while many have been the victims of targeted killings, threats and forced recruitment.

Amid continuing violence this year, thousands more have fled their homes. In the latest episode, more than 1,700 Awá people left their reservations in the south-eastern department of Nariño last month to escape fighting between an irregular armed group and the Colombian military. They have not been able to go back.

Indigenous culture is closely linked to the community's ancestral lands, and forced displacement leads to the loss of traditions, culture and language. To avoid this fate, many communities try desperately to stay on their lands despite the threats and violence. The Bari are one such people – they have refused to move from their land near the border with Venezuela despite the heavy presence of irregular troops and the great risk of violence. Concern is also growing about Embera communities caught up in fighting sweeping Chocó department near the border with Panama.

The relentless pressure and violence has forced many others into flight. Some 1,500 Wounaan people fled their ancestral homelands in April after two of their teachers were murdered by members of an irregular armed group.

"The death of any one of us is terrible, but we especially feel the loss of two teachers," Ulysses, a Wounaan leader, said at the time. "To go and study, to become a schoolteacher, this is not an easy thing for us. We have a unique language, less than a third of our children can read, older people are illiterate. To lose two of our teachers is an awful blow and we feel it very deeply."

Most of the Wounaan have since gone back home despite the continuing insecurity. Ulysses and several others fled to Panama after receiving death threats. They are not the only indigenous people seeking refuge in neighbouring countries.

Some 300 Quechua Indians asked for asylum in Ecuador last November after an armed group entered their reserve in southern Colombia, kidnapped six young girls and threatened the entire population.

"Our worry is great," one indigenous leader forced into exile told UNHCR recently. "We see that our culture is dying, we fear that our young people will lose the traditions of their ancestors and we do not see how the problem will end. It did not start yesterday, but today the violence is worse. What are we going to do? As long as the armed groups are on our territory, we cannot go back."