  We theoretically study magnetization relaxation of Ising spins distributed
randomly in a $d$-dimension homogeneous and Gaussian profile under a soft-core
two-body interaction potential $\propto1/[1+(r/R_c)^\alpha]$ ($\alpha\ge d$),
where $r$ is the inter-spin distance and $R_c$ is the soft-core radius. The
dynamics starts with all spins polarized in the transverse direction. In the
homogeneous case, an analytic expression is derived at the thermodynamic limit,
which starts as $\propto\exp(-t^2)$ and follows a stretched-exponential law
asymptotically at long time with an exponent $\beta=d/\alpha$. In between an
oscillating behaviour is observed with a damping amplitude. For Gaussian
samples, the degree of disorder in the system can be controlled by the ratio
$l_\rho/R_c$ with $l_\rho$ the mean inter-spin distance and the magnetization
dynamics is investigated numerically. In the limit of $l_\rho/R_c\ll1$, a
coherent many-body dynamics is recovered for the total magnetization despite of
the position disorder of spins. In the opposite limit of $l_\rho/R_c\gg1$, a
similar dynamics as that in the homogeneous case emerges at later time after a
initial fast decay of the magnetization. We obtain a stretched exponent of
$\beta\approx0.18$ for the asymptotic evolution with $d=3, \alpha=6$, which is
different from that in the homogeneous case ($\beta=0.5$).
