A wide range of practical systems exhibits dynamics, which are periodic with respect to several state variables and which possess multiple invariant solutions. Yet, when analyzing stability of such systems, many classical techniques often fall short in that they only permit to establish local stability properties. Motivated by this, we present a new sufficient criterion for global stability of such a class of nonlinear systems. The proposed approach is characterized by two main properties. First, it develops the conventional cell structure framework to the case of multiple periodic states. Second, it extends the standard Lyapunov theory by relaxing the usual definiteness requirements of the employed Lyapunov functions to sign-indefinite functions. The stability robustness with respect to exogenous perturbations is analyzed. The efficacy of the proposed approach is illustrated via the global stability analysis of a nonlinear system.