The historical region of Cilicia has existed in the southeast of Asia Minor since ancient times.
In the 1st century BC, the Armenian king Tigran II annexed it to his possessions. Since that time, Armenians began to settle on its territory.
Tigranes II the Great; (140 BC — 55 BC) was the king of Great Armenia, a major commander and conqueror of the Hellenistic era, who ruled in 95-55 BC. The grandson of Artashes I.
Then, these lands were captured by Rome, along with the Armenians who settled there.
In the second half of the 11th century, a mass migration of Armenians from Seljuk-occupied Armenia began in Cilicia. Ruben, the personal bodyguard of the Armenian tsar Gagik II, was one of those who migrated.
He joined the service of the Byzantine commander of Armenian origin Filaret Varazhnuni and was appointed commander of the garrison in Cilicia.
In 1080, Ruben, taking advantage of the weakening of the Greeks, declared the independence of a new state — the principality of Mountainous Cilicia. The Rubenid dynasty began to rule in it.
Ruben I (1025-1095 years of life)
Ruben’s son Kostandin I actively collaborated with the Crusaders and was their ally in the fight against the Seljuks.
Under him, Cilicia expanded due to the lands captured from the Seljuks.
Kostandin I or Konstantin I (1035-1040 / 1050-1055 — 1100 / 24 February, 1102 — February 23, 1103) — the second ruler of Cilician Armenia or «Lord of the Mountains» (1095 — 1100/ 1102 / 1103). During his reign, he controlled most of the region around the Taurus Mountains, and put a lot of effort into cultivating the lands and rebuilding the cities under his command. He provided sufficient provisions to the crusaders, for example, during the difficult period of the siege of Antioch in the winter of 1097. He was a supporter of the division of the Armenian Apostolic Church — Wikipedia
The Cilician state reached its greatest prosperity under Levon I.
The defeated Crusaders ceased to be the main Christian force. The Cilician Armenians moved in their place. Levon captures the lands of the Crusaders and small Armenian principalities voluntarily join Cilicia.
All this has significantly strengthened the power of the state.
The main enemy of Cilicia now became the Byzantines, who captured Cilicia in 1137, and captured Levon, who then died in prison.
But his son Thoros II was able to liberate Cilicia from the Greeks and restored Armenian statehood.
Under the Cilician king Hetum I, the Cilician state became an ally of the Mongols. Together with the Mongols, the Armenians fought against the Egyptian Mamluks.
Hetum I (1213 — October 28, 1270) was the king of Cilician Armenia since 1226, the founder of the Hetumid dynasty. The son of Konstantin Pyle, a cousin of Tsar Levon II. In the history of Armenia, he is the only king who has ruled the country for 45 years. The time of his reign is considered to be the heyday of the culture of Cilician Armenia. In 1270, he abdicated in favor of his son Levon and spent the rest of his life in a monastery, where he died on October 28, 1270 — Wikipedia
Starting with Hetum II, the Cilician kings began to strive to spread Catholicism among the Armenians. This resulted in the resistance of the population to Romanization and the loss of the alliance with the Mongols, who began to attack the territory of Cilicia.
Taking advantage of the weakening of the kingdom, the Mamluks conquered it in 1375. Mountainous Cilicia lasted until 1424, but it was conquered by the Mamluks.