In most historical atlases of Eastern Europe/Asia in the Dark Ages to early medieval period, you see the areas controlled by the Rus/Early Russian principalities in the west and the Volga Bulgars to the east, with various nomadic tribes controlling the southern steppes in turn. Little mention is given to the vast area that lies between these compass points, which comprises the middle Russian highlands within the broad loop of the Volga River. This area roughly encompasses the modern Russian Republic of Mordovia, which is named for the Finno-Ugaric tribes who populated the region from the earliest recorded histories, and who were were dubbed the Mordens (Mordvin) by the Gothic historian Jordanes writting in the 6th Century AD.
In addition to several smaller tribes (Tengushev, the Teryukhan and the Karatay), there were (are) two large and linguistically distinct Mordvin peoples that branched from common Finno-Urgaric roots -- the Moksha, who settled the Oka-Don lowlands in the west, and the Erzya, who settled the Volga uplands in the east. Modern day Mordvin range from fair-headed, grey-eyed and light skinned to dark with black hair and black eyes. As a point of distinction, Erzya commentators often suggest that Mokshan have rounder faces characteristic of the Tatars and Chuvash. Mordvin women are famous for their very colorful dress, and the Mordvin are also famous for their folk music.
According to Jordanes, in the 3rd Century, the Ostrogoth King Hermanaric "subdued many warlike peoples of the north and made them obey his laws" including the "Mordens", who were forced to pay tribute. In the 8th century, the Erzya were tributaries of the Bulgars who settled in the Volga region (Volga Bulgars). The Erzya and Moksha were mentioned in a 10th century diplomatic message by the Khazar Khagan Joseph. In 1172, the Russian principalities of Suzdal, Ryazan and Murom joined forces to conquer the Mordvin capital at Nizhniy Novgorod. Russian expansionism continued, with Muscovy joining in the land grab. Russian peasants were resettled in the region and the colonized terroritory then annexed by the Russian principalities. The Hungarian monk traveller Julianius (Rubrook) traveled through Mordvinia in 1236 AD, taking note of the "Morduans" who were still very warlike and took human heads as trophies.
In the mid-13th Century, the Mordvin suffered the Mongol conquest as it passed enroute from the Volga Bulgars to Russia, and thereafter fell under the rule of the Golden Horde. Eventually, they allied themselves with the Russian resistance. When the last Kazan Khanate fell in 1552 AD, the Mordvinians were annexed to the newly emerging Russian state without significant resistance.
However I disagree with how the army is composd with the preceding article. Supporting on MV Gorelik's 'Warriors of Eurasia' (p.27) we can conclude that steppe-influenced cavalry played a much bigger part in the Mordovian armies than in those of other Finno-Ugrish people. Due to their steppe cavalry panoply consisting of composite bows and light battle axes (very common amongst steppe warriors) among other weapons, they wer eonly subdued in the 12th century which lead to the birth Novgorod.
Other interesting info : http://en.wikipedia.org/wiki/Mordvins
I propose the following list:
RUS - ERA OF THE PRINCES LIST
with the following modifications and restrictions:
-Malaia Druzhina cannot take heavy armour
Influenced by the Rus Cavalry, let in lighter armour as is in line with this army
-1+ unit of Tribal Cavalry and must take bow
The stock Cavalry, influenced by the neighbouring Steppe Tribes.
-no Militia Cavalry
-0-1 Varjazi , no Dane Axe, Wedge Formation or Riding Horses AND must be smaller than any Northern Tribal Warriors Unit
The best and most experienced warriors. The only infantry to carry any armour, I would suggest a mixed troop of Viking, Rus, Berserkers, Wolfskin warrior. Make these look especially fierce.
-No Southern Tribal Warriors
-1+ Northern Tribal Warriors
Stock infantry troops in this army. Use a mixture of Slavs, Poles, Germanics, ...
-No Rus Skirmishers
-1+ Slav Skirmishers
The lesser tribal warriors of Mordovian society
-Only Steppe Nomads can be used as A & M
Bashkirs, Volga Bulgar Allies, other Turkic Nomads all were around and in Mordovia.
I really wonder how this plays in WAB. Almost no armour, yet highly mobile, I think this would make for an interesting challenge.