Abstract The paper intends to explore the various developments that took place over the years in Supply Chain Management. It tries to delve deeper into this context and also highlights the imperative aspects pertinent to it by throwing light on the evolutionary aspects of concepts such as Six Sigma and others. In fact, it has tried to focus upon the innovative concept of Lean by describing in detail what it is about and how it can be very signiicant for the modern day large and complex forms of organizations. Details regarding this along with the methodology and its implications are also given. Furthermore, the assortment of Case Studies emphasizing its substance was also discussed with thorough analysis and illustrations with especial reference to successful lean implementation. It also draws attention to the pioneering idea of Lean manufacturing’s integration with Six Sigma and consequently how it facilitates the process improvement. The instances of corporations such as Lockheed Martin and Bank One are also taken into consideration and especially included in this paper. Keywords: Supply Chain, Six Sigma, Lean, Assortment, Substance The Perplexing Enigma of Supply Chain Management: Literature Review Vibhuti Singh Shekhawat Associate Professor and Head, Department of Humanities & Social Sciences, MNIT Jaipur. Rajasthan, India. Email: vibhutisingh@yahoo.com Introduction Here in this chapter the developments in supply chain management and evolution of Six Sigma are described. Some details on what it is about and its methodology are also given. Some case studies to highlight its importance are also discussed in this literature review. While explaining the concept of lean, case studies of successful lean implementation are also illustrated. It will also brief about Lean manufacturing’s integration with Six Sigma and how it helped in process improvement. Douglas 1 (2004)said, “A streamlined process reduces the order-to-cash cycle which frees up capital, and reduces the delivery lead time which allows for reduced inventory levels.” Defining a Supply Chain It is believed that by necessity science is reductionist. All real-world systems are too complex to study in their totality. So scientists reduce them to a manageable size by restricting their scope and by making simplifying assumptions. For example, all introductory physics students begin their study of mechanics by learning about 1 Professor in Ohio State University of Supply Chain Man- agement objects moving at sub-relativistic speeds in frictionless environments. Although almost all practical mechanical systems violate these conditions, the insights one gains from the stylised systems of classical mechanics are vital to the understanding of more realistic systems. Hence, the friction-free model of moving bodies satisies the fundamental criterion of any scientiic model-it captures an essential aspect of a real system in a form that is simple enough to be tractable and understandable. To get anywhere with a science of supply chains we must irst reduce the complex arrays of suppliers, plants, warehouses, customers, transportation networks and information systems that make up actual supply chains to structures that are simple enough to study rigorously. To do this, we must choose a level at which to model asupply chain. Clearly the level of the entire business is too high; the resulting models would be hopelessly complex and the details would obscure important commonalities between different supply chains. Similarly, the level of an individual operationis too low; while modeling a speciic process (e.g., metal cutting) in detail may betractable, it will give us little insight into what drives the performance metrics (e.g., proit) a manager cares about. Deinition (Supply Chain): A supply chain is a goal- oriented network of processes and stockpoints used to deliver goods and services to customers.