  Using the tight-binding approach, we investigate the energy spectrum of
square, triangular and hexagonal MoS$_2$ quantum dots (QDs) in the presence of
a perpendicular magnetic field. Novel edge states emerge in MoS$_2$ QDs, which
are distributed over the whole edge which we call ring states. The ring states
are robust in the presence of spin-orbit coupling (SOC). The corresponding
energy levels of the ring states oscillate as function of the perpendicular
magnetic field which are related to Aharonov-Bohm oscillations. Oscillations in
the magnetic field dependence of the energy levels and the peaks in the
magneto-optical spectrum emerge (disappear) as the ring states are formed
(collapsed). The period and the amplitude of the oscillation decreases with the
size of the MoS$_2$ QDs.
