A march or mark was, in broad terms, a medieval European term for any kind of borderland, as opposed to a notional "heartland". More specifically, a march was a border between realms, and/or a neutral/buffer zone under joint control of two states, in which different laws might apply. In both of these senses, marches served a political purpose, such as providing warning of military incursions, or regulating cross-border trade, or both.