  It has been claimed that traditional models struggle to explain the tentative
detection of the 21\,cm absorption trough centered at $z\sim17$ measured by the
EDGES collaboration. On the other hand, it has been shown that the EDGES
results are consistent with an extrapolation of a declining UV luminosity
density, following a simple power-law of deep Hubble Space Telescope
observations of $4 < z < 9$ galaxies. We here explore the conditions by which
the EDGES detection is consistent with current reionization and
post-reionization observations, including the neutral hydrogen fraction at
$z\sim6$--$8$, Thomson scattering optical depth, and ionizing emissivity at
$z\sim5$. By coupling a physically motivated source model derived from
radiative transfer hydrodynamic simulations of reionization to a Markov Chain
Monte Carlo sampler, we find that it is entirely possible to reconcile the
high-redshift (cosmic dawn) and low-redshift (reionization) existing
constraints. In particular, we find that high contribution from low-mass halos
along with high photon escape fractions are required to simultaneously
reproduce cosmic dawn and reionization constraints. Our analysis further
confirms that low-mass galaxies produce a flatter emissivity evolution, which
leads to an earlier onset of reionization with gradual and longer duration,
resulting in a higher optical depth. While our faint-galaxies dominated models
successfully reproduce the measured globally averaged quantities over the first
one billion years, they underestimate the late redshift-instantaneous
measurements in efficiently star-forming and massive systems. We show that our
(simple) physically-motivated semi-analytical prescription produces consistent
results with the (sophisticated) state-of-the-art \thesan
radiation-magneto-hydrodynamic simulation of reionization.
