  We model the transmission of the Lyman-alpha line through the circum- and
intergalactic media around dark matter haloes expected to host Lyman-alpha
emitters (LAEs) at z > 5.7, using the high-dynamic-range Sherwood simulations.
We find very different CGM environments around more massive haloes (~10^11
M_sun) compared to less massive haloes (~10^9 M_sun) at these redshifts, which
can contribute to a different evolution of the Lyman-alpha transmission from
LAEs within these haloes. Additionally we confirm that part of the differential
evolution could result from bright LAEs being more likely to reside in larger
ionized regions. We conclude that a combination of the CGM environment and the
IGM ionization structure is likely to be responsible for the differential
evolution of the bright and faint ends of the LAE luminosity function at z > 6.
More generally, we confirm the suggestion that the self-shielded neutral gas in
the outskirts of the host halo can strongly attenuate the Lyman-alpha emission
from high redshift galaxies. We find that this has a stronger effect on the
more massive haloes hosting brighter LAEs. The faint-end of the LAE luminosity
function is thus a more reliable probe of the average ionization state of the
IGM. Comparing our model for LAEs with a range of observational data we find
that the favoured reionization histories are our previously advocated `Late'
and `Very Late' reionization histories, in which reionization finishes rather
rapidly at around z ~ 6.
