We address the puzzling observational indications for very "cold" galactic discs at redshifts $z \gtrsim 3$, an epoch when are expected to be highly perturbed. Using a high-resolution cosmological zoom-in simulation, we identify such cold disc $z\sim 3.5$, with rotation velocity dispersion ratio of $v_\phi/\sigma_r \simeq 5$ total gas. It forms as result period intense accretion co-planar, co-r...