sentences:  Armenia is a unitary, multi-party, democratic nation-state with an ancient cultural heritage.Urartu was established in 860 BC and by the 6th century BC it was replaced by the Satrapy of Armenia.The Kingdom of Armenia reached its height under Tigranes the Great in the 1st century BC and became the first state in the world to adopt Christianity as its official religion in the late 3rd or early 4th century AD.