The concept of MVP deserves some additional explanation. The term was created before the user story mapping technique and is an independent idea. It is also applicable to products that are different from the software code. The goal of the MVP is to maximize the value of the product (in terms of return of investment or, trivially, how useful, popular, and beneficial your product will be) while minimizing the risks and efforts required to build it. The perfect MVP requires a very low level of effort and risk to build, but it can become greatly popular and appreciated when used (and, optionally, sold).
The purpose of an MVP is to start getting feedback on the product from potential end users (usually, a subset of early adopters). Due to this, the MVP should contain a meaningful subset of features: not too many, to avoid wasting effort in case the product is not well received by customers, but just enough in order to represent what the complete product will be like. Early feedback, in the spirit of Agile development methodologies, could also be beneficial if some steering is required in the product direction, by stressing more on one aspect or another.