  Remarkable recent experiments on the moir\'e structure formed by pentalayer
rhombohedral graphene aligned with a hexagonal Boron-Nitride substrate report
the discovery of a zero field fractional quantum hall effect. These
``(Fractional) Quantum Anomalous Hall" ((F)QAH) phases occur for one sign of a
perpendicular displacement field, and correspond, experimentally, to full or
partial filling of a valley polarized Chern-$1$ band. Such a band is absent in
the non-interacting band structure. Here we show that electron-electron
interactions play a crucial role, and present microscopic theoretical
calculations demonstrating the emergence of a nearly flat, isolated, Chern-$1$
band and FQAH phases in this system. We also study the four and six-layer
analogs and identify parameters where a nearly flat isolated Chern-$1$ band
emerges which may be suitable to host FQAH physics.
