The genus is native from east Asia south to northern Australasia.

One species, the Tree-of-Heaven (Ailanthus altissima,) is considered a weed in some parts of the world.

Species include: There is a good fossil record of Ailanthus with many species names based on their geographic occurrence, but almost all of these have very similar morphology and have been grouped as a single species among the three species recognized:[8] A silk spinning moth, the ailanthus silkmoth (Samia cynthia), lives on Ailanthus leaves, and yields a silk more durable and cheaper than mulberry silk, but inferior to it in fineness and gloss.

This moth has been introduced to the eastern United States and is common near many towns; it is about 12 cm across, with angulated wings, and in color olive brown, with white markings.

[3] Other Lepidoptera whose larvae feed on Ailanthus include Endoclita malabaricus.