Vintage Yemeni Inkwell and Writing Utensils Box

A rare First part of the 20th-century Yemeni writing utensils box with three barrel containers.  Traditionally one held ink, another held sand and I am not sure what the third one held.  The barrels are attached to a box that presumably held writing utensils.  

There is a similar box in the British Museum's collection but with only two containers.

• The length of the elongated box is 20 cm (8"). 
• Width is 1.2 cm (1/2") . The compartments are 3.5 cm (1 3/8") in diameter.
• Height is 5 cm (2").
• The piece weighs 185 grams.