Kratom, or mitragyna speciosa, is a plant native to Southeast Asia (Thailand, Indonesia, Malaysia, Myanmar, and Papua New Guinea) whose leaves have psychoactive properties. The leaves have been chewed, brewed into tea, and otherwise used for medicinal properties since at least the beginning of the 19th century.
In Thailand, kratom has even been "used as a snack to receive guests and was part of the ritual worship of ancestors and gods." Workers would chew on the plant’s leaves to increase energy and stave off exhaustion, and the leaves or extracts from them have been used to heal wounds––acting as a local anesthetic.