The importance of pan-tropical connections on Tropical Pacific Decadal Variability is gradually emerging in scientific literature. Recent analysis suggests that until 1980, both the Indian (IO) and the Atlantic Ocean (AO) modulated the Pacific Ocean (PO) with each ocean basin dominating in different time periods. That is, in certain years the IO appears to have had a stronger influence on the Pacific whereas, at other times, the AO appears to have had a stronger influence. However, post-1980, the AO appears to have taken command in driving Pacific variability, and the IO influence appears to have weakened. The cause of the recent AO dominance in these pan-tropical connections is unknown and thus is a matter of prominent scientific interest. The present study explores how decadal changes in the background state of the IO and AO modulate the Pacific climate. In particular, we compare the effect of decadal SST variations in the IO and AO on Pacific rainfall and circulation patterns given consistent background and variability of Pacific SSTs. The study also seeks to understand why the inter-basin relationships have changed over time and how these changes impact on ENSO.