Other Spanish bagpipes are also found in Catalonia (``sac de gemecs''), the Balearic Islands (``xeremia''), Zamora (``gaita zamorana'' and the probably better known ``gaita sanabresa''), Logroño (``gaita logroñesa'')... The Cantabrian gaita is, as far as I know, almost the same as the Asturian one. Gaitas have been used in Aragón, though for some time the traditional Aragonese gaita (``gaita de boto'') was very difficult to find, and Galician-like gaitas were used instead. Nowadays there are a couple of makers who produce this type of bagpipe, which has a drone parallel to the chanter in a common stock.
It is supposed that there was also a Basque bagpipe, now extinct, called, I believe, ``Xaranbel''. I have not found any reliable reference about it.
I suppose that bagpipes were broadly played in Spain in the middle
age. There are reproductions of bagpipers in Romanic churches and
Monasteries built in the XI century and pictures of bagpipers in the
Court of the King Alfonso X El Sabio, dating back to the XIII century
(e.g., those found in the ``Cantigas de Santa María'' [Songs in
Praise of Saint Mary].
Here is a picture of a
bagpiper playing an instrument with two
drones, and a picture of
two bagpipers playing droneless
Galician bagpipes come in lots of flavors. There used to be bellows blown gaitas galegas (named ``gaita de barquín''), but they are scarce (or better, almost extinct) now. The current gaita galega is a mouth blown beast. (N.b.: in a recent mail, Pedro Silva tells me he and some friends are trying to bring the bellows blown Galician bagpipe back to life, taking an old picture as basis. I definitely would like to see it!)