At 12:01 a.m. on Aug. 29, the historic cease-fire between the Revolutionary Armed Forces of Colombia — a Marxist guerrilla group known as FARC — and the Colombian government was in place, bringing to an end a 52-year-old conflict. In the coming months, thousands of FARC troops will relinquish their weapons and rejoin civil society, bringing hope to a country scarred by too many deaths. “Never again will parents be burying their sons and daughters killed in the war,” said Rodrigo Londoño, FARC’s leader.

For the past 12 years, Spanish photographer Alvaro Ybarra Zavala has been following the FARC guerrilla. He speaks to TIME about his experience.

Alice Gabriner: Why do you think this peace agreement is significant?

Alvaro Ybarra Zavala: The peace agreement between FARC and the government offers the first opportunity, after many generations, for Colombia to change through a framework of peace and dialogue, putting an end to a war that has raged in Colombia since 1964. In terms of Latin American history, it is as pivotal as the dismantling of the Berlin Wall. During the Cold War, the U.S. opposed the Marxist FARC, fearing that Colombia would follow the path of Cuba. For the Colombian government, the U.S. and its allies, a peace agreement means they are willing to accept their enemy as a legal political party, which now has the possibility to bring social change in Colombia, where other left-wing governments in Latin America have failed, most notably in Venezuela.

Gabriner: When did you take your first trip to cover FARC in Colombia?

Ybarra Zavala: My first contact with FARC was in 2004. I wanted to do a story in an area under their control. However, it wasn’t until 2007 that I had full access with them. Then, for six months, I was documenting in and out of their territory, particularly in the San Juan River in Chico state. I have maintained contact with FARC and lived in guerrilla camps six times over the years, documenting their activities all over Colombia, especially in the region of Caqueta where FARC is particularly visible. In Colombia, you need the agreement of the armed groups in order to work, and FARC controls a major part of the country.

Gabriner: How did you arrange access?

Ybarra Zavala: Access to FARC has changed a lot since 2004 and 2007, when my contacts were militants and FARC collaborators who helped me [get close to] the commanders. This is how I worked in Chico and Caqueta until the beginning of the peace talks in Havana. Once the negotiations began, it was necessary to work through channels in Cuba in order to make contact with the guerrillas. Access with FARC has always been difficult and complicated, because of all the different armed groups in those areas. Plus, FARC distrusts everyone from the outside.

Gabriner: Why do people join FARC? What was the attraction for the local population?

Ybarra Zavala: In many regions of Colombia, for the civilian population, the Colombian state represents only bombs and war, nothing more. In these regions FARC acted as the governing body tending to the needs of the local people because the state was not present. Poor people in regions under FARC control are victims of abuse by right-wing paramilitaries and the army, simply because they were born there, and therefore assumed to be collaborators. For these people, FARC represented the only alternative in helping bring change to the established order all over Colombia.

Gabriner: FARC has long been associated with the drug trafficking? How will the drug trade in Colombia be affected by this peace deal?

Ybarra Zavala: Since the fall of the Berlin Wall and the Soviet Union, coca has been the main source of funding for the guerrillas. They controlled the territory and the business of illicit crops. Coca has been, and is, the only source of funding for the families of these regions neglected by the state. The guerrillas guaranteed purchase of all production from the territories under its control, which allowed families to survive. After the peace agreement, the big question is: What real alternatives are there for thousands of families from these poor regions? Will the state fulfill all of its commitments in relation to social investment in these regions as an alternative to illicit crops? To inculcate this peace agreement is not enough. Just as armed peace, social peace is necessary. It is more important than ever to provide alternative opportunities for the people who have lived in the shadows. Without that, Colombia will never have real peace.

Gabriner: Why do you think both sides are willing to embrace peace now?

Ybarra Zavala: The Colombian people are tired of war and violence. Colombian society has had enough. They want the killing between brothers to stop.

Gabriner: As a photographer, what is your biggest challenge having covered this story for so long?

Ybarra Zavala: My biggest challenge is to photograph the contradicting reality in Colombia. There is not just one Colombia, but many different fractured parts that share the common denominator of war. This vast country is divided by invisible but quite real borders that have given rise to parallel states. This fact has opened up deep wounds, insurmountable hatred and absolute truths that take shape as unquestioned dogmas. Worst of all is that memories of the conflict have been erased. Colombians must face truths about the past in order to move towards forgiveness and reconciliation. The objective of my work is to expose the legacy of violence, hatred and distress that should not be forgotten. To quote my good friend, Eduardo, “The wind sweeps away the traces of seagulls. Rain sweeps away the traces of humans. The sun sweeps away the traces of time. Photography searches for the traces of lost memories, love and pain, that cannot be seen, but that cannot be swept away.”

This interview has been edited for length and clarity.

A book of Alvaro Ybarra Zavala’s work will be published in December.

Follow TIME LightBox on Facebook, Twitter and Instagram.