  We have measured rapidity densities dN/dy of pions and kaons over a broad
rapidity range (-0.1 < y < 3.5) for central Au+Au collisions at sqrt(snn) = 200
GeV. These data have significant implications for the chemistry and dynamics of
the dense system that is initially created in the collisions. The full
phase-space yields are 1660 +/- 15 +/- 133 (pi+), 1683 +/- 16 +/- 135 (pi-),
286 +/- 5 +/- 23 (K+) and 242 +/- 4 +/- 19 (K-). The systematics of the strange
to non--strange meson ratios are found to track the variation of the
baryo-chemical potential with rapidity and energy. Landau--Carruthers
hydrodynamic is found to describe the bulk transport of the pions in the
longitudinal direction.
