Armenia is a unitary, multi-party, democratic nation-state with an ancient cultural heritage. The Kingdom of Van was established in 860 BC and by the 6th century BC it was replaced by the Satrapy of Armenia. In the 1st century BC the Kingdom of Armenia reached its height under Tigranes the Great. Armenia became the first state in the world to adopt Christianity as its official religion.In between the late 3rd century to early years of the 4th century, the state became the first Christian nation. The official date of state adoption of Christianity is 301 AD. The ancient Armenian kingdom was split between the Byzantine and Sasanid empires around the early 5th century. Under the Bagratuni dynasty, the Armenian Kingdom was restored in the 9th century. Declining due to the wars against the Byzantines, the kingdom fell in 1045 and Armenia was soon after invadedby the Seljuk Turks. An Armenian principality and later a kingdom Cilician Armenia was located on the coast of the Mediterranean Sea between the 11th and 14th centuries.