  We perform a detailed study of stringy moduli-driven cosmologies between the
end of inflation and the commencement of the Hot Big Bang, including both the
background and cosmological perturbations: a period that can cover half the
lifetime of the universe on a logarithmic scale. Compared to the standard
cosmology, stringy cosmologies motivate extended kination, tracker and
moduli-dominated epochs involving significantly trans-Planckian field
excursions. Conventional effective field theory is unable to control
Planck-suppressed operators and so such epochs require a stringy completion for
a consistent analysis. Perturbation growth in these stringy cosmologies is
substantially enhanced compared to conventional cosmological histories. The
transPlanckian field evolution results in radical changes to Standard Model
couplings during this history and we outline potential applications to
baryogenesis, dark matter and gravitational wave production.
