Eastern Iranian language in the context of "Zarathustra"

Zarathushtra Spitama, more commonly known as Zoroaster or Zarathustra, was an Iranian religious reformer who challenged the tenets of the contemporary Ancient Iranian religion, becoming the spiritual founder of Zoroastrianism. In the oldest Zoroastrian scriptures, the Gathas, which he is traditionally believed to have authored, he is described as a preacher and a poet-prophet. Some have claimed, with much scholarly controversy, to find his influence in Heraclitus, Plato, Pythagoras, and, perhaps less controversially, in the Abrahamic religions, including Judaism, Christianity, and Islam, particularly through concepts of cosmic dualism and personal morality.

He spoke an Eastern Iranian language, named Avestan by scholars after the corpus of Zoroastrian religious texts written in that language. Based on this, it is tentative to place his homeland somewhere in the eastern regions of Greater Iran (perhaps in modern-day Afghanistan or Tajikistan), but his exact birthplace is uncertain. His life is traditionally dated to sometime around the 7th and 6th centuries BC; though most scholars, using linguistic and socio-cultural evidence, suggest a dating to somewhere in the second millennium BC.

Sogdia (/ˈsɒɡdiə/) or Sogdiana was an ancient Iranian civilization between the Amu Darya and the Syr Darya rivers, and in present-day Uzbekistan, Turkmenistan, Tajikistan, Kazakhstan, and Kyrgyzstan. Sogdiana was also a province of the Achaemenid Empire, and listed on the Behistun Inscription of Darius the Great. Sogdiana was first conquered by Cyrus the Great, the founder of the Achaemenid Empire, and then was annexed by the Macedonian ruler Alexander the Great in 328 BC. It would continue to change hands under the Seleucid Empire, the Greco-Bactrian Kingdom, the Kushan Empire, the Sasanian Empire, the Hephthalite Empire, the Western Turkic Khaganate, and the Muslim conquest of Transoxiana.

The Sogdian city-states, although never politically united, were centered on the city of Samarkand. Sogdian, an Eastern Iranian language, is no longer spoken. However, a descendant of one of its dialects, Yaghnobi, is still spoken by the Yaghnobis of Tajikistan. It was widely spoken in Central Asia as a lingua franca and served as one of the First Turkic Khaganate's court languages for writing documents.

Bactrian (Bactrian: Αριαο, romanized: ariao, Bactrian pronunciation: [arjaː], meaning "Iranian") was an Eastern Iranian language formerly spoken in the Central Asian region of Bactria (present-day Afghanistan) and used as the official language of the Kushan and the Hephthalite empires.

Kangju (Chinese: 康居; pinyin: kāngjū; Wade–Giles: K'ang-chü; Eastern Han Chinese: kʰɑŋ-kɨɑ < *khâŋ-ka (c. 140 BCE)) was the Chinese name of a kingdom in Central Asia during the first half of the first millennium CE. The name Kangju is now generally regarded as a variant or mutated form of the name Sogdiana. According to contemporaneous Chinese sources, Kangju was the second most powerful state in Transoxiana, after the Yuezhi. Its people, known in Chinese as the Kāng (康), were evidently of Indo-European origins, spoke an Eastern Iranian language, and had a semi-nomadic way of life. The Sogdians may have been the same people as those of Kangju and closely related to the Sakas, or other Iranian groups such as the Asii.

Yaghnobi is an Eastern Iranian language spoken in the upper valley of the Yaghnob River in the Zarafshan area of Tajikistan by the Yaghnobi people. It is considered to be a direct descendant of Sogdian and has sometimes been called Neo-Sogdian in academic literature. There are some 12,500 Yaghnobi speakers, divided into several communities. The principal group lives in the Zafarobod area. There are also resettlers in the Yaghnob Valley. Some communities live in the villages of Zumand and Kůkteppa and in Dushanbe or its vicinity.

Most Yaghnobi speakers are bilingual in Tajik, a dialect of Persian. Yaghnobi is mostly used for daily family communication, and Tajik is used by Yaghnobi-speakers for business and formal transactions. A Russian ethnographer was told by nearby Tajiks, long hostile to the Yaghnobis, who were late to adopt Islam, that the Yaghnobis used their language as a "secret" mode of communication to confuse the Tajiks. The account led to the assumption by some that Yaghnobi or some derivative of it was used as a secret code.