Tacrolimus (FK506, Prograf, Advagraf etc.) was discovered in 1984 in Mt. Tsukuba in Japan. The historic, sacred mountain of Mount Tsukuba is situated approximately 60 km northeast of Tokyo in the central-eastern region of the Japanese archipelago. Rising 877 m above sea level, it comprises 2 distinct peaks.  Importantly, tacrolimus has its origins in Mount Tsukuba. Tacrolimus was discovered during screening for immunosuppressive activity in compounds isolated from the fermentation broths of Streptomyces tsukubaensis, a bacteria found in the soil.