Kočna is the site of a mass grave from the period immediately after the Second World War. The Kočna Mass Grave, also known as the Poljane nad Jesenicami Mass Grave, is located southeast of the settlement, a few dozen meters from a dirt road. It is a visibly sunken area measuring and it contains the remains of up to 40 Germanprisoners of war murdered on 7 or 10 May 1945. One of the intended victims was able to escape.
Excavations in 1982 at the Jamnik Rock Shelter east of the settlement revealed artifacts from the Mesolithic era. The finds included a bone harpoon blade.