  Ba-enhanced stars are interesting probes of stellar astrophysics and Galactic
formation history. In this work, we investigate the chemistry and kinematics
for a large sample of Ba-enhanced ([Ba/Fe]$>$1.0) dwarf and subgiant stars with
$5000 < T_{\rm eff }< 6700$\,K from LAMOST. We find that both stellar internal
evolution process and external mass exchange due to binary evolution are
responsible for the origins of the Ba-enhancement of our sample stars. About
one third of them exhibit C and N enhancement and ultraviolet brightness
excess, indicating they are products of binary evolution. The remaining
Ba-enhanced stars with normal C and N abundances are mostly warm stars with
$T_{\rm eff} > 6000$\,K. They are likely consequences of stellar internal
elemental transport processes, but they show very different elemental patterns
to the hotter Am/Fm stars. Our results reveal a substantially lack of
high-[$\alpha$/Fe] Ba-enhanced stars in the [Fe/H]--[$\alpha$/Fe] plane, which
we dub as a {\em high-$\alpha$ desert}. We suggest it is due to a lower
efficiency for producing Ba-enhanced stars by low-mass AGB progenitors in
binary systems. Our results call for detailed modellings for these Ba-enhanced
stellar peculiars, in the context of both stellar internal elemental transport
and external mass accretion.
