In Dhofar, where Frankincense trees are mostly to be found, they grow in a belt along the northern flank of the coastal mountains, where they are not directly affected by the monsoon rains.

The quality of the frankincense resin is dependent on the humidity of the location. The best quality comes from boswellia sacra trees in dry regions away from the coastal areas. Its resin is yellowish white, having a clear consistency and is named after Nejd, an area north of the Dhofar mountains. The resin from trees further south, nearer the monsoon’s watershed, is darker in colour, less pure, and is called shazri. The lowest quality, shaabi, comes from the wetter coast. There is also a noticeable East-West divide in the quality of the produce, known in the trade as olibanum – the best quality comes from the East of the distribution area.

Harvesting the resin is an art in itself. Using a special knife, known as a Mingaf, shallow incisions are made in several places in the trees bark. The incision should be just enough to induce the manufacture of resin, but must not seriously damage the tree in any way. Initially, only small, white drops of a sticky, milky fluid are exuded – this resin is worthless and after some three weeks is simply scraped away. Only now does the actual olibanum make its appearance. The ‘pearls’, or ‘tears’, are harvested at intervals of three weeks, mainly during the hot spring months.

After harvesting over a maximum of three years, the trees are left for several years in order to recover.

The increasing interest in frankincense today is not just due to the prize-winning luxury perfume, Amouage, which contains olibanum. In the meantime, Western medicine has begun to discover the precious resin. Clinical trials using medicinal compounds based on boswellic acids, have shown promising results in patients with rheumatoid arthritis, chronic colitis, ulcerative colitis and bronchial asthma, as well as Crohn’s disease.