In 2012, investigative journalist Aidan Hartley was granted unprecedented access to what is considered the largest known cache of raw ivory in the world. Hartley’s report is part of the National Geographic film Battle for the Elephants, which explores the brutal slaughter of African elephants for their tusks.

In this clip from the film, Hartley meets with Khamis Kagasheki, minister of natural resources for Tanzania, who agreed to allow Hartley and a camera crew to take the first-ever footage of the stockpile. The vast warehouse stores thousands of tusks accumulated over the last 23 years—90 metric tons valued at $50 million. You will follow Hartley into the “ivory room”—a grim memorial to the dramatic decline of Africa’s elephant population.

In July 1989, Kenya issued a call-to-action to alert the world to a poaching crisis. Then President Daniel arap Moi, together with then Executive Director of Kenya Wildlife Service Dr. Richard Leakey, burned 12 tons of ivory stock.

In September of that year, the Convention on International Trade in Endangered Species (CITES) secured an agreement among its member states to ban all international trade in ivory. But, under pressure from countries in Asia and southern Africa, CITES sanctioned two sales of ivory, in 1999 and 2008—stimulating poaching across the elephant range and ivory smuggling across the world.

In 2011, Kenya again drew attention to poaching deaths when President Mwai Kibaki set fire to more than 5 tons of ivory tusks and trinkets.

Unlike Kenya, Tanzania, one of the poorest countries in the world, has not agreed to burn its stockpile of ivory, arguing that the money from a sale could support conservation efforts. However, Tanzanian officials say that if an international agency were to buy the tusks with the intention of burning them, they would eagerly sell them. Tanzania asked CITES for an exception to the ivory ban for such a sale, with proceeds used only for conservation efforts, but they withdrew their request in early 2013.