Ruairi Glasheen is an award-winning percussionist, composer, documentary-maker and educator based in London.

(CNN) I first encountered the tonbak -- Iran's indigenous drum -- as a student, when I heard it on an old LP I found in a dusty corner of the library at London's Royal College of Music. Instantly, I was hooked.

A small, goblet-shaped drum, the tonbak is rarely seen or heard outside Iran, but it drives the fast and frenetic rhythmic intensity of Persian classical music.

Ruairi Glasheen hones his Iranian drumming skills with tonbak expert Javad Alirezaei.

The tonbak is usually made of walnut, ash or pear wood and topped with a thin piece of camel or goat skin. Musicians play with their hands, sitting down with the drum resting sideways across their legs.

Earlier this year, I traveled to Iran in search of the tonbak and to make The Hidden Drummers of Iran -- a crowdfunded documentary film about my quest.

In Esfahan, a historic city in central Iran, I met renowned tonbak player Jafar Ghazi Asgar, who runs a music academy with his wife, Melika Davoodi. According to Davoodi, young tonbak players are drumming life into this ancient art form -- thanks in part to Instagram. Google, Facebook and Twitter are banned in Iran, but Instagram is permitted and provides a haven for young players to share their music.

Percussionist Ruairi Glasheen.

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