  Context. The Galactic Center (GC) region has been studied in gamma rays in
the past decades - the GC excess detected by Fermi is still not fully
understood and the first detection of a PeVatron by H.E.S.S. indicates the
existence of sources that can accelerate cosmic rays up to a PeV or higher.
  Aims. In this paper, we are investigating the origin of the PeVatron emission
detected by H.E.S.S. by, for the first time, simulating cosmic rays in the GC
in a realistic three-dimensional gas and photon field distribution and
large-scale magnetic field.
  Methods. We solve the 3D transport equation with an anisotropic diffusion
tensor using the approach of stochastic differential equations as implemented
in the propagation software CRPropa 3.1 (Merten et al. 2017). We test five
different source distributions for four different configurations of the
diffusion tensor, i.e. with ratios of the perpendicular to parallel components
$\epsilon = 0.001,\ 0.01,\ 0.1,\ 0.3$.
  Results. We find that the two-dimensional distribution of gamma rays as
measured by H.E.S.S. is best fit by a model that considers three cosmic-ray
sources, i.e. a central source, the SNR G0.9+0.1 and the source HESS J1746-285.
The fit indicates that propagation is dominated by parallel diffusion with $
\espilon = 0.001 $.
  Conclusions. We find that the 3D propagation in the 3D gas and B-field
configurations taken from Guenduez et al. (2020) can explain the general
features of the data well. We predict that CTA should be able to identify
emission from SgrB2 and the six dust ridge clouds that are included in our
simulations and that should be detectable with a the expected resolution of CTA
of 0.033$^\circ$.
