One of the vulcanization reaction mechanisms of rubber, which has been technically and scientifically developed and refined since 1839, is reviewed. This is the reaction mechanism for the N-cyclohexyl-2-benzothiazole sulfenamide (CBS) based vulcanization, which is still a conventional compounding system in the rubber industry, but the details of the reaction mechanism have not been fully clarified. This paper focuses on the role of a new reaction intermediate, dinuclear bridging bidentate zinc/stearate complex, generated from zinc oxide and stearic acid, or zinc stearate for the CBS based vulcanization reaction of isoprene rubber. The electron transfer effect from the diene rubber to the complexes is shown to be a main factor promoting the vulcanization reaction, and the π-electron cloud of the rubber molecule is also reported to lead to the formation of a highly uniform rubber network with good dispersions of the complexes in the rubber matrix. Namely, it is emphasized that the rubber is both a substrate and a solvent in the vulcanization reaction, and that the combination of diene rubber and these reagents is an origin of the sophisticated vulcanization. The content of this review will provide useful suggestions for the development of rubber science and technology.