Boriana/Boryana (both spellings are right) is a female form of
Boris, and as far as I know, it's as old as
Boris (which means very old!).
As the site says,
Boris is commonly (and mistakenly) considered to be the short form of
Borislav. The proposers of this theory, however, have still to explain why there is
Stanislav but not Stanis,
Jaroslav and not Jaros, etc.
According to my sources,
Boris was a name used by the proto-Bulgarians (and probably other Turkic tribes) from before they mingled with the Slavs. There are several theories about its origin. It might mean wolf (from the Turkic bjori), tiger (from the Altaian bars), but the one I personally tend to agree with is that the name was derived from the Mongolian bogoris - short. The proto-Bulgarians used the names
Boris and Bogoris interchangeably which has lead some to believe that
Boris is actually short from Bogoris.
The name was considered to be pagan up until the 860s when
Boris I converted Bulgaria to Christianity. A century later the Russian great knyaz (?)
Vladimir I who converted Kiev Russia to Christianity (988-989) named one of his sons
Boris. According to the Russian historic sources,
Boris and his brother
Gleb were the children of
Vladimir I by "some Bulgarian". They were killed around 1015 by their step-brother
Svyatopolk who later claimed the Russian throne. A few years later they were both canonized, and as far as I know, st.
Boris and
Gleb are still revered in not only Russia, but also in Belorussia and Ukraine. From Russia the name spread to the neighboring countries, but until the turn of the 20th century it was mainly used in the royal families of Eastern Europe. In Russia it became popular for the common folk after the October revolution (1918); in Bulgaria it regained its popularity after the birth of the heir to the throne
Boris III (the father of the now-prime-minister
Simeon).
Of course, there are no such recordings of the name Boriana but most historians believe it is the female form of
Boris and has been used for a looooooooooong time.
Hope that helps :)