The precision cosmic microwave background (CMB) measurement and a hint of neutral hydrogen 21cm line observation tell us a lot about the CMB propagation during the dark and reionization eras of the Universe. Beside a significant boost towards precision cosmology, this newly acquired understanding of the CMB signals can be turned into a powerful test of potential imprints on to the standard astrophysical/cosmic history from beyond the Standard Model physics: injection of the energy from the annihilation, decays or radiation from dark matter or black holes. Upcoming CMB polarization experiments and 21cm measurements on the cosmic ionization history will bring the prospective sensitivity to such new physics processes to a whole new level.