The Alat (a.k.a. Ala-at, Ala, Alachin, Alagchin, Alchin, Alchi, Alayontli, Ulayundluğ (اُوﻻيُنْدْلُغْ) ("piebald horse", pinto); Boma (駁馬 or 駮馬 "piebald horse"), Helai (賀賴), Helan (賀蘭), Hela (曷剌), Bila (弊剌), or dru-gu ha-la-yun-log ("Ha la yun log Turks")) were one salient Turkic tribe known from Chinese annals.

Alats were possibly identical to the Luandi, or Xueyantuo, or Khalajes, the last group being a Turkic Central Asian people known to medieval Arab and Persian Muslim geographers and in Bactrian inscriptions.

Literature on Alats is very rich; Alats were a subject of study by Tangshu, Jiu Tangshu, Tang Huiyao, N.Ya. Bichurin, S.E. Malov, N.A. Aristov, Grigory Grum-Grshimailo, Yu. Nemeth, G. Howorth, P. Pelliot, L. Hambis, and others.

In ancient Turkic lexicon, the meaning of "skewbald" (horse) is expressed with the terms "ala" or "alagchin" still active now in composite expressions. Tang Huiyao mentioned, right after the Ashina tribe, a tribe named Geluozhi[ya] (葛羅枝[牙]) (Middle Chinese ZS: *kɑt̚-lɑ-t͡ɕiᴇ[-ŋˠa]), whose tamga is depicted as . Zuev took this as a variant of 遏羅支 Eluozhi (supposedly from MC *a-la-tsie) and asserted that this is the earliest transmission and certainly ascends to Alagchin (Alachin, Alchin, Alchi). During the Tang period, Chinese chroniclers calqued the ethonym Alat as Boma "skewbald horses". Elsewhere, Zuev stated that "Sometimes the tribal name 曷剌 Hela (< ɣа-lât < *alat < *ala-at "skewbald horse") is written down with hieroglyphs 賀賴 Helai (ɣâ-lâi < alai), which is equivalent to 賀蘭 Helan (< alan ~ ala "skewbald, motley, mixed"). Since Oghuz (Turkmen) tribe of Alayontli has the same tamga as Boma (Alat) tribe and whose name also translates as "skewbald horse", Zuev is certain that Alayontli is the same tribe as alat.

Chinese historiographers also preserved many similar titles, individual and tribal names in Xianbei society, where horses were held in high esteem:

According to Peter A. Boodberg the title Helazhen transcribes "undoubtedly *atlačin 'horseman' from Tk. atla 'to mount a horse'", thus "a purely Turkish form in T'o-pa". All of those foresaid names & titles are traceable back to Turkic or Turco-Mongol *atlan "to ride" < *at- "horse", whereas *ala- *alaɣ-, or *alutu means "variegated", "dappled", or "piebald", thus describing the preferred coat-color(s) of nomadic northerners' warhorses.

The ethnonym Alat might have been transcribed as Khalaj or Qalaj in Persian, Arabic and Bactrian sources, corresponding to 訶(達)羅支 He(da)luozhi (< *ha-(dat-)la-tɕĭe) or 葛(達)羅支 Ge(da)luozhi (< *kat-(dat-)la-tɕĭe), which in turn are variants of 葛羅支 Geluozhi. According to the New Book of Tang (vol. 217), Boma 駁馬 ~ Bila 弊剌 ~Eluozhi 遏羅支 neighboured the Jiegu 結骨 (i.e. Yenisei Kyrgyz). Arab geographer al-Idrisi recorded that the Khalajes' winter quarter and castle were situated near the Kimeks, who in turn dwelt in the Irtysh basin, to the north and/or west of the Kirghizes. Thus, based on geographic arrangements, the Boma ~ Bila ~ Eluozhi (i.e. Alats) might be the same as Khalajes.

Tongdian glossed Helan as simply "horse" in Old Turkic and Yuanhe Maps and Records of Prefectures and Counties glossed Helan as "piebald horse",