The antiquities trade is the exchange of antiquities and archaeological artifacts from around the world. This trade may be illicit or completely legal. The legal antiquities trade abides by national regulations, allowing for extraction of artifacts for scientific study whilst maintaining archaeological and anthropological context. The illicit antiquities trade involves non-scientific extraction that ignores the archaeological and anthropological context from the artifacts. The legal trade in antiquities abide by the laws of the countries in which the artifacts originate. These laws establish how the antiquities may be extracted from the ground and the legal process in which artifacts may leave the country. In many countries excavations and exports were prohibited without official licenses already in the 19th century, as for example in the Ottoman Empire. According to the laws of the countries of origin, there can't be a legal trade with archaeological artifact without official papers. However, most national laws still overturn these regulations. Illicit or illegal antiquities are those found in illegal or unregulated excavations, and traded covertly. The black market trade of illicit antiquities is supplied by looting and art theft. Artifacts are often those that have been discovered and unearthed at archeological digs and then transported internationally through a middleman to often unsuspecting collectors, museums, antique dealers, and auction houses. The antiquities trade is much more careful in recent years about establishing the provenance of cultural artifacts. Some estimates of billions of dollars in annual sales are demonstrably false. The true extent of the trade is unknown as incidents of looting are underreported. It is not unheard of for stolen pieces to be found in auction houses before they have been noticed as missing from their original home. It is believed by many archaeologists and cultural heritage lawyers that the demand created by circulation, marketing, and collectorship of ancient artifacts causes the continuous looting and destruction of archaeological sites around the world.