Agarwood is a resinous heartwood that sometimes occurs in trees belonging to the genus Aquilaria (Thymelaeceae family). Aquilaria is a fast-growing, archaic subtropical forest tree, with a population range stretching from South Asia’s Himalayan foothills, throughout Southeast Asia, and into the rainforests of Papua New Guinea. It grows at elevations from a few meters above sea level to about 1000 meters, with approx. 500 meters being most ideal. Aquilaria can grow on a wide range of soils, including poor sandy soil. Seedlings require a great deal of shade and water but will grow rapidly, producing flowers and seeds as early as four years old. At least fifteen species of Aquilaria are known to produce the much sought-after agarwood. In South Asia, particularly India, Aquilaria achalloga is found. Aquilaria malaccensis is mostly known from Malaysia and Indonesia, while Aquilaria crassna grows primarily in Indochina. A number of others are also known, such as Aquilaria grandfolia, Aquilaria chinesis etc., though these are relatively minor species for agarwood production.