  We analyze the existence of the exotic $\Theta^+$ from the perspective of
instanton induced quark dynamics. The 't Hooft interaction gives strong
attraction in specific channels of the triquark $ud\bar s$ and diquark $ud$
configurations. In particular it leads to a light $ud\bar s$ triquark cluster,
with the mass around $750 {\rm MeV}$, in the I=0, $S=1/2$ and color 3
configuration, and a light $ud$-diquark configuration, with mass $440 {\rm
MeV}$, in the I=0, S=0 and color {$\bar{3}$} configuration. If we consider the
pentaquark as a bound state of such triquark and diquark configurations in a
relative L=1 state we obtain good agreement with the data. The small width of
$\Theta^+$ has a natural explanation in this model.
