  We analyze the experimental data for the magnetic susceptibility of the
material ZnCu3(OH)6Cl2 in terms of the Kagome Lattice Heisenberg model (KLHM),
discussing possible role of impurity spins, dilution, exchange anisotropy, and
both out-of-plane and in-plane Dzyaloshinsky-Moriya (DM) anisotropies, with
explicit theoretical calculations using the Numerical Linked Cluster (NLC)
method and exact diagonalization (ED). The high-temperature experimental data
are well described by the pure Heisenberg model with J=170 K. We show that the
sudden upturn in the susceptibility around T=75 K is due to DM interactions. We
also observe that at intermediate temperatures, below T=J, our calculated
susceptibility for KLHM fits well with a power law T^{-0.25}.
