According to a modern etymology, the term Azerbaijan derives from that of Atropates, a Persian satrap under the Achaemenid Empire, who was later reinstated as the satrap of Media under Alexander the Great. The original etymology of this name is thought to have its roots in the once-dominant Zoroastrianism. In the Avesta's Frawardin Yasht ("Hymn to the Guardian Angels"), there is a mention of , which literally translates from Avestan as "we worship the fravashi of the holy Atropatene". The name "Atropates" itself is the Greek transliteration of an Old Iranian, probably Median, compounded name with the meaning "Protected by the (Holy) Fire" or "The Land of the (Holy) Fire". The Greek name was mentioned by Diodorus Siculus and Strabo. Over the span of millennia, the name evolved to (Middle Persian), then to , , (New Persian) and present-day Azerbaijan. The name Azerbaijan was first adopted for the area of the present-day Republic of Azerbaijan by the government of Musavat in 1918, after the collapse of the Russian Empire, when the independent Azerbaijan Democratic Republic was established. Until then, the designation had been used exclusively to identify the adjacent region of contemporary northwestern Iran, while the area of the Azerbaijan Democratic Republic was formerly referred to as Arran and Shirvan. On that basis Iran protested the newly adopted country name. During the Soviet rule, the country was also spelled in Latin from the Russian transliteration as (). The country's name was also spelled in Cyrillic script from 1940 to 1991 as . History Antiquity The earliest evidence of human settlement in the territory of Azerbaijan dates back to the late Stone Age and is related to the Guruchay culture of Azykh Cave. Early settlements included the Scythians during the 9th century BC. Following the Scythians, Iranian Medes came to dominate the area to the south of the Aras river. The Medes forged a vast empire between 900 and 700 BC, which was integrated into the Achaemenid Empire around 550 BC. The area was conquered by the Achaemenids leading to the spread of Zoroastrianism. From the Sasanid period to the Safavid period The Sasanian Empire turned Caucasian Albania into a vassal state in 252, while King Urnayr officially adopted Christianity as the state religion in the 4th century. Despite Sassanid rule, Albania remained an entity in the region until the 9th century, while fully subordinate to Sassanid Iran, and retained its