  We have investigated the long-term evolution of individual anomalous X-ray
pulsars (AXPs) and soft gamma repeaters (SGRs) with relatively well constrained
X-ray luminosity and rotational properties. In the frame of the fallback disc
model, we have obtained the ranges of disc mass and dipole field strength that
can produce the observed source properties. We have compared our results with
those obtained earlier for dim isolated neutron stars (XDINs). Our results show
that (1) the X-ray luminosity, period and period derivative of the individual
AXP/SGR sources can be produced self-consistently in the fallback disc model
with very similar basic disc parameters to those used earlier in the same model
to explain the long-term evolution of XDINs, (2) except two sources, AXP/SGRs
are evolving in the accretion phase; these two exceptional sources, like XDINs,
completed their accretion phase in the past and are now evolving in the final
propeller phase and still slowing down with the disc torques, (3) the dipole
field strength (at the poles) of XDINs are in the $10^{11}-10^{12}$ G range,
while AXP/SGRs have relatively strong dipole fields between $1-6 \times
10^{12}$ G, and (4) the source properties can be obtained with large ranges of
disc masses which do not allow a clear test of correlation between disc masses
and the magnetic dipole fields for the whole AXP/SGRs and XDIN population.
