Friction stir welding (FSW) is an eco-friendly and solid-state joining technology. Due to this reason, industries are keenly adopting this joining process in their various applications e.g., automobile, aerospace, marine, etc. Several materials have already been welded by FSW including aluminum, copper, steel, alloys of these materials, plastics, composites, and list are still going on. Few researchers have welded the brass using FSW. In this research, yellow brass 405-20 is welded with FSW for the very first time. Thermal distribution during FSW of brass was recorded via both simulations and experiments. Moreover, ultimate tensile strength was also measured numerically with its validation from its empirical counterpart. Finally, hardness was measured numerically in the form of compressive strength of welded brass, and it was also validated experimentally. Three aspects of validated simulations were never studied for brass 405-20 before and finally a good and close match was found between results from both simulations and experiments.