Skin mast cells (MCs) are distinct from other MCs, and for years, we have tried to understand their origin and peculiarities. A recent study demonstrated that during development, MCs enter the skin from the yolk sac and embryonic liver and are later mixed with cells originating from the bone marrow. A report from Weitzmann et al. (2020) shows that MCs or their precursors occupy distinct areas in the fetal period and that they and their progeny maintain these geographic distributions throughout life. These stable clonal territories are altered only by the arrival of bone marrow‒derived MCs during inflammation.