Armenia has an ancient history which comes from the centuries. All along the time borders of Armenia were expanding or were shrinking, neighboring countries were changing as well.
Some nations rose and built their countries and others just vanished. During all this time the countries near Armenia tried to conquer this peace-loving country. Among those were Assyria, Persia, Rome, Byzantium.
Anyway Armenia was able to resist and reach up to the 21st century. Now the Republic of Armenia constitutes only one-tenth of historical Armenia and borders with Turkey to the West, Georgia to the North, Nagorno-Karabakh Republic and Azerbaijan to the East, and Iran and Azerbaijan exclave of Nakhichevan to the South.
Very few of those countries has so deep roots as Armenia and was in the turmoil of the ancient history.