The region that today constitutes the United States–Mexico borderland has evolved through various systems of occupation over thousands of years. Beginning in time immemorial, the land was used and inhabited by ancient peoples whose cultures we can only understand through the archeological record and the beliefs of their living descendants. Spain, then Mexico and the United States after it, attempted to control the borderlands but failed when confronted with indigenous power, at least until the late 19th century when American capital and police established firm dominance. Since then, borderland residents have often fiercely contested this supremacy at the local level, but the borderland has also, due to the primacy of business, expressed deep harmonies and cooperation between the U.S. and Mexican federal governments. It is a majority minority zone in the United States, populated largely by Mexican Americans. The border is both a porous membrane across which tremendous wealth passes and a territory of interdiction in which noncitizens and smugglers are subject to unusually concentrated police attention. All of this exists within a particularly harsh ecosystem characterized by extreme heat and scarce water.