The Tatars (Old Turkic: 𐱃𐱃𐰺; Chinese: 大檀, 檀檀, 塔塔), also known by their Mongolic name Naıran (Chinese: 芮芮, 柔然, 蠕蠕), were a Turkic tribe ruled by a Särbi or Mongolized Xuŋa elite. They were originally a Tägäräk tribe known as the He-tu-lin (紇突鄰).
Tentative Classification as Turkic in Origin
The Tatar Qağanate was formed when a subtribe of the Tägäräk tribe, known as the He-tu-lin tribe (紇突鄰 LH *ɣuət-tʰuət-lin), came under the leadership of Moquraq, a former slave of probable Särbi origin. This is likely the reason why the annals of the Central States cannot agree on an origin for them.
The earliest source on their origin, the Book of Song 95 claims that:
The Rui-rui (芮芮) are also known as Tatars (大檀), also spelled as Tatars (檀檀), and are a subgroup of the Xuŋa.
Similarly, the next source on their origin, the Book of Liang 54 claims that:
The Rui-rui (芮芮) state was established by a subgroup of the Xuŋa.
Only the Book of Wei 103 claims that they are descendants of the Dong-hu, or Särbi:
The Ru-ru (蠕蠕) are the descendants of the Dong-hu (東胡).
In their early days, the Tatars probably continued to practice Turkic customs. However, following the collapse of the Xuŋa, the Särbi began to dominate the steppe. Thus, the practice of and association with Mongolic culture, like it did centuries later under the Mongol Empire, became the new status quo. It is to be expected that the Tatars, a group that was now ruled by a Särbi elite and inhabited Särbi lands, would gradually become Mongolized.
The Tatar ethnonym, from Turkic *tɑt “foreigner,” likely began as an exonym for the He-tu-lin tribe, who were likely seen as foreigners akin to the Mongolized Tabğaç. This is perhaps reflected in the Mongolic name for the Tatars, transcribed variously as:
Rui-rui - 芮芮 – LH *ńuas-ńuas
Rou-ran - 柔然 – LH *ńu-ńan
Ru-ru - 蠕蠕 – LH *ńo- ńo