The Yenisei Host was formed in 1917 from the Krasnoyarsk and Irkutsk Regiments. Tiny and spread out over a huge distance (it is 800 km from along the Yenisei river around Krasnoyarsk east to Irkutsk and Lake Baikal, with no direct links) it had no significant political presence.
The Yenisei area initially was not much affected by the revolutions as it was too far north, away from the railway and industry. Irkustsk and Krasnoyarsk themselves went Soviet, but that did not affect the countryside very much. The Cossacks themselves were firmly counter-revolutionary, but in insufficient numbers to make any difference outside their own stanitsas.
When the Czechs revolted they conquered Irkutsk fairly quickly in their desperate attempt to get the Lake Baikal tunnels before they could be destroyed. There seems to have been no Cossack involvement at this time. A White government was set up in the town. Krasnoyarsk fell eventually, when the Siberian Host cleared the area. From this period they were loyal to the Provisional Siberian Government, the Ufa Directory and then Kolchak in turn.
White Cossack regiments were raised from the Yenisei, rising to a Yenisei Brigade, and also a separate Irkutsk Regiment.
There may have also been a Khakas unit recruited in the area, led by a Khakas speaking Cossack (the Khakas were inorodtsy). A Khakas Divizion appears to have served with the Siberian Cossacks, rather than Yenisei.
While not initially very revolutionary, the excesses of the Siberian regime soon led to growing partisan groups in region: two of the more famous partisan groups were those of Pëtr Shchetinkin and Alexandr Kravchenko. The Yenisei Cossacks raised were busy fighting on these internal fronts, but sent a couple of sotnias to help clear the Perm area early on, before the partisan menace grew.
Following the collapse of Kolchak's army in late 1919, the Yenisei and Irkutsk areas were swamped by a massive wave of partisans in winter 1919/1920. The Red Army proper followed soon afterwards. The Yenisei Brigade retreated east, and make it relatively unscathed. The Irkutsk Cossack Regiment seems to have been destroyed at Yansk.
The Far Eastern Army in Chita still included the Yenisei Cossack Brigade some 700 strong, in two regiments and a battery. Some then 450 reached Primorye with Ataman Kazantsev, half on foot, as the Yenisei Cossack Divizion. Eventually they were absorbed into the Composite Cossack Regiment as their strength dwindled.
Some other Yenisei served with General Bakich in China and Ungern-Sternberg in Mongolia, a large part of the Host having emigrated southwards.
The uniform of the Yenisei was yellow distinctions. They therefore resemble TransBaikal Cossacks in every respect.
Historically the units had a cipher of "И" for the Irkutsk and "К" for the Krasnoyarsk branches, but the situation in 1918 is not clear. When in the Far East, the cipher became "E" for Yenisei units.
Volkov, S.V. "Encyclopedia of the Civil War: the White Movement", Neva, 2002
Sheksheev A., "The Antibolshevik Movement in the Yenisei Cossack Host", at a-pesni.org
Novikov, "The Antibolshevik Movement in the Irkutsk Cossack troops. A brief historical sketch" at a-pesni.org
Tarasov M, "The Yenisei Cossacks in Mongolia During the Civil War Period", Journal of Siberian Federal University, at elib.sfu-kras.ru (pdf)