The problem of decentralized control is considered for a class of linear time-varying large scale systems with uncertainties and external disturbances in the interconnections. In the paper, the upper bounds of the uncertainties and external disturbances are assumed to be unknown, and control inputs are represented by the nonlinear functions satisfying the condition of the series nonlinearity. The adaptation laws are proposed to estimate such unknown bounds, and by making use of the updated values of these unknown bounds, a class of decentralized state feedback controllers are constructed. It is shown that by employing the proposed decentralized state feedback controllers, the solutions of the resulting adaptive closed-loop large scale system can be guaranteed to be uniformly ultimately bounded.