While cannabis plants have been grown since at least the 3rd millennium BCE,[33] evidence suggests it was being smoked for psychoactive effects at least 2,500 years ago in the Pamir Mountains.[34] Since the early 20th century, cannabis has been subject to legal restrictions. The possession, use, and cultivation of cannabis is illegal in most countries of the world.[35][36] In 2013, Uruguay became the first country to legalize recreational use of cannabis.[37] Other countries to do so are Canada, Georgia, and South Africa. In the United States, ten states and the District of Columbia have made the drug legal under local law, although these laws are still technically superseded by federal law banning the drug.[37] Medical use of cannabis, requiring the approval of a physician, has been legalized in a greater number of countries.[38]