  Towards the end of brane inflation, the brane pair annihilation produces
massive closed strings. The transfer of this energy to Standard Model (SM) open
string modes depends on where the SM branes and the brane annihilation are
located: in the bulk, in the same throat or in different throats. We find that,
in all cases as long as the brane annihilation and the SM branes are not both
in the bulk, the transfer of energy to start the hot big bang epoch can be
efficient enough to be compatible with big bang nucleosynthesis. The
suppression of the abundance of the graviton and its Kaluza-Klein (KK) thermal
relics follows from the warped geometry in flux compactification. This works
out even in the scenarios where a long period of tunneling is expected. In the
multi-throat scenario, we find a dynamical mechnism of selecting a long throat
as the SM throat. We establish three new dark matter candidates: KK modes with
specific angular momentum in the SM throat, those in the brane annihilation
throat, and different matters generated by KK modes tunneled to other throats.
Since the latter two couple to the visible matter sector only through graviton
mediation, they behave as hidden dark matter. Hidden dark matter has novel
implications on the dark matter coincidence problem and the high energy cosmic
rays.
