[en] Experiments using light ion beams of atomic masses A ∼ 30 have been underway since 1986 at the Brookhaven AGS and the CERN SPS at the respective energies √s ∼ 5 A GeV and 20 A GeV. The first truly heavy ion runs with a gold beam began this spring at the AGS. In this talk I will survey our progress towards an understanding of nuclear collision dynamics, focusing on those issues that are relevant to Au+Au at the AGS. In view of what we have already learned from the light ion data, I will argue that the prospects for producing matter at extreme density in these experiments are excellent