  Exactly soluble string theories describing a particular hadronic sector of
certain confining gauge theories have been obtained recently as Penrose-Gueven
limits of the dual supergravity backgrounds. The effect of taking the
Penrose-Gueven limit on the gravity side translates, in the gauge theory side,
into an effective truncation to hadrons of large U(1) charge (annulons). We
present an exact calculation of the finite temperature partition function for
the hadronic states corresponding to a Penrose-Gueven limit of the
Maldacena-Nunez embedding of N=1 SYM into string theory. It is established that
the theory exhibits a Hagedorn density of states.
  Motivated by this exact calculation we propose a semiclassical string
approximation to the finite temperature partition function for confining gauge
theories admitting a supergravity dual, by performing an expansion around
classical solutions characterized by temporal windings. This semiclassical
approximation reveals a hadronic energy density of states of Hagedorn type,
with the coefficient determined by the gauge theory string tension as expected
for confining theories. We argue that our proposal captures primarily
information about states of pure N=1 SYM, given that this semiclassical
approximation does not entail a projection onto states of large U(1) charge.
