[1] Tanev was born in Gevgelija, in the Salonica Vilayet of the Ottoman Empire (present-day North Macedonia) and joined the Bulgarian Communist Party in 1919.
After the failure of the September Uprising of 1923 he fled to the Kingdom of Yugoslavia, then moved between Communist Russia and secret missions in Bulgaria.
On 9 March 1933 Tanev, Dimitrov and Blagoy Popov, along with others were arrested and charged with complicity in the Reichstag fire.
[1] Tanev was acclaimed as a hero on his return to Russia, but was forced into self-denunciation later in the 1930s.
The Bulgarian Communist Party ordered him to carry out a mission in Bulgaria in 1941.