Progress in the Study of Multi-quark States

The progress in the study of multi-quark states for the last half century is reviewed schematically and the dibaryon sector is emphasized. By employing the dynamical symmetry, the Gursey-Radicati mass formula, which can give a reasonable description of the masses of multi-quark states, can be reproduced. The dibaryons in bag model and realistic quark model, quark delocalization color screening model, are discussed.