The Early Cyrillic alphabet, also called classical Cyrillic or paleo-Cyrillic, is an alphabetic writing system that was developed in Bulgaria in the Preslav Literary School during the late 9th century
View of the cave monastery near the village of Krepcha, Opaka Municipality in Bulgaria. Here is the oldest Cyrillic inscription dated of 921.
The Cyrillic alphabet on birch bark document № 591 from ancient Novgorod (Russia). Dated to 1025–1050 AD.
Gospels of Tsar Ivan Alexander
I is a letter used in almost all modern Cyrillic alphabets with the exception of Belarusian, where it is replaced by І.
И, from Alexandre Benois' 1904 азбука.
In early Russian typewriters like this one, there was no key for the digit 1, so the capital І was used instead. Following the Russian alphabet reform of 1918, a 1 key was added.