Short answers, pulled from the story.
The Kingdom of Cappadocia emerged in 331 BC as one of Alexander the Great's successor states. The Ariarathid dynasty ruled this Anatolian territory for over two centuries until 95 BC.
Ariobarzanes I became king with military support from Governor Lucius Cornelius Sulla in 95 BC. This action established Cappadocia as a client kingdom under the Republic following Senate demands for independence.
Germanicus arrived in the East in 18 AD and annexed Cappadocia directly into the Empire reducing it to a province. Tiberius had summoned Archelaus to Rome earlier that same year before his death.
Cappadocia retained three legions and several auxiliary units totaling over 28,000 troops stationed across the region. These forces served as an important response against invasions from the Parthian Empire.
Emperor Valens split the south-western region around Tyana in 371 creating Cappadocia Secunda under a praeses while the remainder became Cappadocia Prima under a consularis. The eastern half had already formed Armenia Prima and Armenia Secunda in the late 330s.