Western Turkic Khaganate in the context of "620s"

The Khazars (/ˈxɑːzɑːrz/) were a semi-nomadic Turkic people who established a major commercial empire in the late 6th century CE spanning modern southeastern Russia, southern Ukraine, and western Kazakhstan. It was the most powerful polity to emerge from the break-up of the Western Turkic Khaganate. Astride a major artery of commerce between Eastern Europe and Southwestern Asia, Khazaria became one of the foremost trading empires of the early medieval world, commanding the western marches of the Silk Road and playing a key commercial role as a crossroad between China, the Middle East, and Kievan Rus'. For some three centuries (c. 650–965), the Khazars dominated the vast area extending from the Volga-Don steppes to the eastern Crimea and the northern Caucasus.

Although they were likely a confederation of different Turkic-speaking peoples, the precise origins and nature of the Khazars are uncertain, since there is no surviving record in the Khazar language and the state was multilingual and polyethnic. Their native religion is thought to have been Tengrism, like that of the North Caucasian Huns and other Turkic peoples, although their multiethnic population seems to have included pagans, Jews, Christians, and Muslims. Although there is evidence that the ruling elite of the Khazars had converted to Rabbinic Judaism in the 8th century, the scope of the conversion to Judaism within the khanate remains uncertain.

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.

Tengrism (also known as Tengriism, Tengerism, or Tengrianism) is a belief system originating in the Eurasian steppes, based on shamanism and animism. It generally involves the titular sky god Tengri. According to some scholars, adherents of Tengrism view the purpose of life as to be in harmony with the universe.

It was the prevailing religion of the Göktürk, Hun, Xianbei, Bulgar, Xiongnu, Yeniseian and Mongolic peoples, as well as the state religion of several medieval states such as the First Turkic Khaganate, the Western Turkic Khaganate, the Eastern Turkic Khaganate, Old Great Bulgaria, the First Bulgarian Empire, Volga Bulgaria, Khazaria, and the Mongol Empire. In the Irk Bitig, a ninth century manuscript on divination, Tengri is mentioned as Türük Tängrisi (God of Turks). According to many academics, Tengrism was, and to some extent still is, a predominantly polytheistic religion based on the shamanistic concept of animism, and was first influenced by monotheism during the imperial period, especially by the 12th–13th centuries. Abdulkadir Inan argues that Yakut and Altai shamanism are not entirely equal to the ancient Turkic religion.

The Eastern Turkic Khaganate (Chinese: 東突厥; pinyin: Dōng Tūjué or Dōng Tújué) was formed as a result of the destructive wars in the beginning of the 7th century (AD 581–603) after the First Turkic Khaganate (founded in the 6th century in the Mongolian Plateau by the Ashina clan) had splintered into two polities – one in the east, one in the west. The Eastern Turkic Khaganate was defeated and absorbed by the Tang dynasty, and Xueyantuo occupied the territory of the former Turkic Khaganate.