Extremely rare and endangered - Overharvesting and habitat loss threatens many populations of agarwood-producing species. Concern over the impact of the global demand for agarwood has thus led to the inclusion of the main taxa on CITES Appendix II, which requires that international trade in agarwood is subject to controls designed to ensure that harvest and exports are not to the detriment of the survival of the species in the wild - for that reason it is seldom that I stock the item as I am concerned only with the conservation and ethical supply of the product.

Agarwood plantations have been established in a number of countries. The success of these plantation depends on the stimulation of agarwood production in the trees. Numerous inoculation techniques have been developed, with varying degrees of success.

One of the reasons for the relative rarity and high cost of agarwood is the depletion of the wild resource. Since 1995 Aquilaria malaccensis, the primary source, has been listed in Appendix II (potentially threatened species) by the Convention on International Trade in Endangered Species of Wild Fauna and Flora. In 2004 all Aquilaria species were listed in Appendix II; however, a number of countries have outstanding reservations regarding that listing.

Agarwood (or just Agar) is a dark resinous heartwood that forms in Aquilaria trees (large evergreens native to southeast Asia) when they become infected with a type of mould. Prior to infection, the heartwood is relatively light and pale coloured, however as the infection progresses, the tree produces a dark aromatic resin in response to the attack, which results in a very dense, dark, resin embedded heartwood. The resin embedded wood is commonly called gaharu, jinko, aloeswood, agarwood, or oud not to be confused with Bakhoor and is valued in many cultures for its distinctive fragrance, and thus is used for incense and perfumes.

The aroma of agarwood is complex and pleasing, with few or no similar natural analogues. As a result, agarwood and its essential oil once gained great cultural and religious significance in ancient civilizations around the world, being mentioned throughout one of the world's oldest oral texts - the Sanskrit Vedas from India.

In as early as the 3rd century, the chronicle Nan zhou yi wu zhi (Strange things from the South) written by Wa Zhen of the Eastern Wu Dynasty mentioned agarwood produced in the Rinan commandery, now Central Vietnam, and how people collected it in the mountains.

Starting in 1580 after Nguyen Hoang took control over the central provinces of modern Vietnam, he encouraged trade with other countries, specifically China and Japan. Agarwood was exported in three varieties: Calambac (kỳ nam in Vietnamese) trầm hương (very similar but slightly harder and slightly more abundant) and agarwood proper.

A pound of Calambac bought in Hoi An for 15 taels could be sold in Nagasaki for 600 taels. The Nguyen Lords soon established a Royal Monopoly over the sale of Calambac. This monopoly helped fund the Nguyen state finances during the early years of the Nguyen rule.

Xuanzang's travelouges and the Harshacharita, written in 7th century A.D. in Northern India mentions use of Agarwood products such as 'Xasipat' (writing-material) and 'aloe-oil' in ancient Assam (Kamarupa). The tradition of making writing-materials from its bark still exist in Assam.

There are fifteen species in of the Aquilaria genus and eight are known to produce agarwood. In theory agarwood can be produced from all members; however, until recently it was primarily produced from Aquilaria malaccensis. Aquilaria agallocha and Aquilaria secundaria.

A. crassna and A. sinensis are the other two members of the genus that are usually harvested.

Formation of agarwood occurs in the trunk and roots of trees that have been infected by a parasitc ascomycetous mould, Phaeoacremonium parasitica, a dematiaceous (dark-walled) fungus. As a response, the tree produces a resin high in volatile organic compounds that aids in suppressing or retarding the fungal growth. While the unaffected wood of the tree is relatively light in colour, the resin dramatically increases the mass and density of the affected wood, changing its colour from a pale beige to dark brown or black. In natural forest only about 7% of the trees are infected by the fungus. A common method in artificial forestry is to inoculate all the trees with the fungus.

High quality resin comes from a tree's natural immune response to a fungal attack. It is commonly known as agarwood 1 (first quality). An inferior resin is created using forced methods where aquilaria trees are deliberately wounded, leaving them more susceptible to a fungal attack. This is commonly called agarwood 2.