The Indian Postal Administration in the 19th. and 20th. centuries (up to India's attainment of Independence in 1947) extended far beyond the geographical limits of the sub-continent itself and included such distant points as East Africa and the Straits Settlements of Malaya.
In a number of British-controlled areas scattered around the Indian Ocean, Indian stamps were used to prepay postage until the establishment of local postal systems (still under the general control of British India) permitted these areas to issue their own stamps (and thereby garner the revenues therefrom).
In the Persian Gulf area also, the I.P.A operated a number of Agencies to serve the British- and Indian-controlled trading houses who controlled all of the Gulf trade at that time.
Indian stamps used in these places can only be identified by their postmarks and while this is relatively easy for the more recent CDS-type cancel,, it is rather more difficult with the older, numbered, postmarks.
Selections of these 'Used Abroads' lend added spice, not only to collections of India itself, but also to those of those countries that used Indian stanps before issuing their own.
So, the next time you're sorting through a dealer's stock of old Indian cheapies (and who has not whiled away many a sunny Saturday afternoon doing just that?), keep an eye out for these; you could do your collection quite a bit of good!
Where Abroad Indian Stamps were used?
East Africa: Lamu, Mombasa, Zanzibar.
Arabia: Aden.
Mesopotamia: Bagdad, Basra.
Persia(Iran): Bandar-Abbas, Bushire, Linga, Mahommera.
Persian Gulf Agencies: Bahrain, Dubai, Kuwait, Muscat and Guadur.
French Settlements in India: Chandernagore, Karikal, Mahe, Pondicherry, Yanam.
Portuguese Settlements in India: Damaun, Goa.
East Asia: Nepal, Sikkim, Tibet, Burma, Straits Settlements.
This is not a complete list; places for which examples are rare have been omitted, as has most mail from military campaigns.
INDIAN CANCELLATIONS
The cancellations of India is a moderately huge topic, to which entire books have been devoted. I'll therefore cover only the essentials.
Up until 1861, the Indian Postal Service was divided into several areas or 'circles', each centered on a major city or state, each having it's own distinctive cancellation types.
Agencies outside India were attached to one or another circle, depending on their geographical location.
In deference to the India Study Circle I'll use the standard numbering for the cancellation types. There are numerous sub-types especially amongst the All-India cancellations.
AREA (CIRCLE) TYPES