  By combining a model for the evolution of the radio luminosity of an
individual source with the radio luminosity function, we perform a
multi-dimensional Monte-Carlo simulation to investigate the cosmological
evolution of the Fanaroff-Riley Class II radio galaxy population by generating
large artificial samples. The properties of FRII sources are required to evolve
with redshift in the artificial samples to fit the observations. Either the
maximum jet age or the maximum density of the jet environment or both evolve
with redshift. We also study the distribution of FRII source properties as a
function of redshift. From currently available data we can not constrain the
shape of the distribution of environment density or age, but jet power is found
to follow a power-law distribution with an exponent of approximately -2. This
power-law slope does not change with redshift out to z=0.6. We also find the
distribution of the pressure in the lobes of FRII sources to evolve with
redshift up to $z\sim1.2$.
