1) Merya. Capital Galich-Mersky, Galich of Merya. In the province of Vetluga, a separate vassal state of Mari can be created.
The leader of Merya is Dmitry Shemyakahttps://en.wikipedia.org/wiki/Dmitry_Shemyaka, who in 2 years will become the Grand Duke of Muscovy.
Surely, among his peers and associates, Meryans and "Meryano-Russians" were in the majority, since his nickname Shemyaka is Meryan-Mari. In the XV-XVI centuries. it was widely used in the Upper Volga region, and later recorded as a Mari proper name. Meaning - "dark" (dark-haired / swarthy). Or maybe so: "Darkest" - with an emphasis not on appearance, but on character.
2) Mozhaisk. The leader Ivan of Mozhaisk https://ru.wikipedia.org/wiki/Иван_Андреевич_(князь_можайский) is Merya's ally.
3) Viatka is an independent pirate republic. They are also Merya's allies.
4) Horde of Ulu Muhammad https://en.wikipedia.org/wiki/Ulugh_Muhammad. Former Khan of the Golden Horde, who was defeated by Kuchuk Muhammad. He is at war with Muscovy because the former vassal does not want to pay tribute when the overlord lost.
5) Suzdal. The leader - Vasily Shuiskyhttps://ru.wikipedia.org/wiki/Шуйский,_Василий_Юрьевич - is the offspring of an ancient dynasty.
6) Bulgaria. Leader - Ali-bek. Ruined by plague, frequent wars and pirates, this pale shadow of the former power of the last descendants of the Huns. They observed the decline of Islam and a return to Tengrism, Turumism - from the Chuvash language.
8) Muscovy. Leader - Vasily II https://en.wikipedia.org/wiki/Vasily_II_of_Moscow. Leads the fight with the former overlord, Ulu Mohammed.