This paper develops an approach to modeling and analyzing the overall dynamics of monodisperse particulate systems in a horizontal rotating drum under time-varying drum rotational speeds. This approach captures the above collective dynamics using stochastic models in the form of Markov chains. The characteristics of such dynamics can be obtained from the Markov chain operator. It provides a systematic way to the analysis of features of collective particle movements, which is in contrast to the existing qualitative analysis. In this paper, Markov chains models are developed based on DEM simulation results to show the effectiveness of the proposed approach. The obtained operators are used to estimate the spatial particle distribution and particulate mixing as examples of collective dynamic features of particulate systems. (C) 2013 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.