Task: Question Generation
Input (English): Armenia established a Church that still exists independently of both the Catholic and the Eastern Orthodox churches, having become so in 451 AD as a result of its stance regarding the Council of Chalcedon. Today this church is known as the Armenian Apostolic Church, which is a part of the Oriental Orthodox communion, not to be confused with the Eastern Orthodox communion. During its later political eclipses, Armenia depended on the church to preserve and protect its unique identity. The original location of the Armenian Catholicosate is Echmiadzin. However, the continuous upheavals, which characterized the political scenes of Armenia, made the political power move to safer places. The Church center moved as well to different locations together with the political authority. Therefore, it eventually moved to Cilicia as the Holy See of Cilicia.
Output (English): When did Armenia's church become independent?