  It is shown that all possible N sheeted coverings of the cylinder are
contained in type IIA matrix string theory as non-trivial gauge field
configurations. Using these gauge field configurations as backgrounds the large
$N$ limit is shown to lead to the type IIA conformal field theory defined on
the corresponding Riemann surfaces. The sum over string diagrams is identified
as the sum over non-trivial gauge backgrounds of the SYM theory.
