The Kathiri State of Seiyun in Hadhramaut was a part of the Aden Protectorate until 1967. In the eastern part of Yemen near Oman, Kathiri issued its own stamps from 1942 to 1964.
At first, Kathiri stamps were in denominations of rupees, annas, and pies, but in 1951, as with other Aden stamps (including those of the nearby Quaiti Sultanate), Kathiri began using shillings and cents.
Kathiri stamps are an important part of any Aden or Yemen stamp collection. Check the current selection, which changes daily.