  Recent experiments on rhombohedral pentalayer graphene flakes with a
substrate induced moir\'e potential have identified both Chern insulators and
fractional Quantum Hall states in the absence of an applied magnetic field.
Surprisingly, these states are observed in strong displacement fields where the
effects of the moir\'e lattice are weak, and seem to be readily accessed
without fine-tuning. To address these experimental puzzles we study an
interacting model of electrons in this geometry, first within the
self-consistent Hartree-Fock (SCHF) approximation. We find an isolated Chern
band with Chern number $|C|=1$, that moreover is relatively flat and shows good
quantum geometry. Exact diagonalization and density matrix renormalization
group methods at fractional filling establish the presence of fractional
quantum anomalous Hall (FQAH) states. The $|C|=1$ band in SCHF is remarkably
robust to varying microscopic parameters, and is also found in the $N_L=4$ and
$N_L=6$ layer systems. Remarkably, it appears stable even to switching off the
moir\'e potential, pointing to spontaneous breaking of translation symmetry. We
term this topological crystalline state the ``anomalous Hall crystal" (AHC),
and argue that it constitutes a general mechanism for creating stable Chern
bands in rhombohedral graphene. Our work elucidates the physics behind the
recent rhombohedral pentalayer graphene observations, predicts the appearance
of the same phase in other systems, and opens the door to studying the
interplay between electronic topology and spontaneous translation symmetry
breaking.
