  We analyze the baryon sideward and elliptic flow from SIS (0.25 $\sim$ 2 A
GeV) to AGS (2 $\sim 11.0A$GeV) energies for Au + Au collisions in the
relativistic transport model RBUU that includes all baryon resonances up to a
mass of 2 GeV as well as string degrees of freedom for the higher mass
continuum. There are two factors which dominantly determine the baryon flow at
these energies: the momentum dependence of the scalar and vector potentials and
the resonance-string degrees of freedom. We fix the explicit momentum
dependence of the nucleon-meson couplings within the NL3 parameter set by the
nucleon optical potential up to 1 GeV of kinetic energy. When assuming the
optical potential to vanish identically for $E_{kin} \geq 3.5$ GeV we
simultaneously reproduce the sideward flow data of the FOPI, EOS, E895 and E877
collaborations, the elliptic flow data of the EOS, E895 and E877
collaborations, and approximately the rapidity and transverse mass distribution
of protons at AGS energies. The gradual change from hadronic to string degrees
of freedom with increasing bombarding energy can be viewed as a transition from
{\it hadronic} to {\it string} matter, i.e. a dissolution of hadrons.
