The recently escavated Qesem and Tabun caves however suggest the oldest period is about 350 kyr and the most recent 200 kyr.
Tabun-Khara-Obo is an impact crater in the Dornogovi Aimag (province) the south-east of Mongolia.
The use of tabun was opposed by Hitler's Minister of Armaments, Albert Speer, who, in 1943, brought IG Farben's nerve agent expert Otto Ambros to report to Hitler.
After the war, the Allies recovered German artillery shells containing three new nerve agents developed by the Germans (Tabun, Sarin, and Soman), prompting further research into nerve agents by all of the former Allies.