X-ray and optical spectral properties of three X-ray obscured radio galaxies at z > 3 obtained by this study. Top: X-ray spectra of the three obscured radio galaxies at z > 3. All three sources are spec-z confirmed sources. The left panel is ERO_ID = 3682, z = 3.10, log(N_H/cm⁻²) = 22.1. The middle panel is ERO_ID = 3933, z = 3.09, log(N_H/cm⁻²) = 22.1. The right panel is ERO_ID = 7772, z = 3.11, log(N_H/cm⁻²) = 22.0. The best-fit model and its 99% confidence interval are displayed as blue shaded regions. For each source, the lower panel displays the ratio to the best-fit model. Bottom: optical spectra of the three obscured radio galaxies at z > 3. The spectra for ERO_ID = 3682 and 7772 are taken from the SDSS survey (Abdurro’uf et al. 2022) and the spectrum for ERO_ID = 3933 is taken from the WiggleZ survey, which uses AAT/AAOmega spectrograph (Drinkwater et al. 2018).