Two of the factors which influence the summer monsoon rainfall variability over the East Asian Domain are the El Nino and Southern Oscillation (ENSO) phenomenon and the recently identified Indian Ocean Dipole Mode (IODM). In this study impact of IODM and ENSO on the East Asian monsoon variability has been studied using observational data and modeling studies. Results reveal that the dipole mode influences the summer monsoon activity over East Asia, in particular the Korea-Japan sector three seasons later and ENSO affects monsoon variability over China simultaneously. This study has also identified one possible mechanism of the delayed impact of the dipole mode over the Indian Ocean on the summer monsoon variability over East Asia. General Circulation Model was used to investigate this mechanism. The delayed impact three seasons later is carried by the snow distribution over Eurasia. The snow distribution over Eurasia serves as a bridge connecting Indian Ocean and East Asian monsoon variability.