The beginning of Tigran’s expansion had been purely local, but his next move brought him into conflict with Roman interests. His marriage to Cleopatra, the daughter of Mithradates VI of Pontus, caused him to support his father-in-law’s attempt to annex the neighboring kingdom of Cappadocia, whose ruler was a client of Rome (Justin, 38.3.1-3). 1
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[Cleopatra] was one of the daughters of King Mithridates VI of Pontus and Queen Laodice. Cleopatra is sometimes known as Cleopatra the Elder, to distinguish her from her sister of the same name and was born and raised in the Kingdom of Pontus. She was the wife of the Armenian King Tigranes the Great....
Tigranes chose a foreign policy different from that of Mithridates towards the Roman Republic based on his interests, and he eventually signed a treaty with Rome following the Battle of Artaxata in 68 BC, as a result of which Cleopatra, under the influence of her father, instigated their sons to betray Tigranes. In 66 BC, Pompey captured the younger Tigranes and took him to Rome as a hostage. Tigranes later escaped in 58 BC with the assistance of Publius Clodius Pulcher. Roman historian Asconius described the event. The sons attempted unsuccessfully to seize the throne from Tigranes; Zariadres and his younger brother were executed by Tigranes.
Cleopatra escaped to her father and lived the remainder of her life in Pontus. 2