The Sheikah tribe kept to themselves in their village(s) of Kakariko and came to be distinctively marked by the genetic traits of red eyes and an inborn affinity to shadow magic. Sheikah were thus masters both in the art of magic and that of fighting because of their skills in stealth and a martial art of their own. Typically Sheikah warrior would wear tight clothing to not be hindered in battle and sometimes protective armors and or bandages to conceal themselves. Sheikah mages instead supposedly wore very large clothes and possibly turbans. With their abilities, the Sheikah created several magical artefacts of superb quality, such as the Lens of Truth, the so called Gossip Stones or the Magic Sword.
Since the Hylians' golden age, the Sheikah always served the Royal Family of Hyrule, but it is rumored that on one occasion the Royal Family betrayed their loyalty and that the Sheikah consequently added a tear to their symbol, the eye of shadows. As a certain fact, after the Civil War of Hyrule the Sheikah were pretty much extinct, their very village being repopulated by Hylians, and in the following ages, they were all but forgotten. However, very few of them seem to have survived, some of these, continuing to serve Hyrule (the Royal Family in particular) while others may have devoted themselves entirely to the darkness.
There are no records of this tribe ever existing in Termina (at least, not with a social identity of their own), but it is possible that the Garo spies which attacked Ikana had some connection to their Terminian counterparts.