Inspired by This Thread
GLOSSARY
Ærth: Earth
Æropa: Europe
Atlantl (a-tlan-tl): Atlantis
Teclan: Successors to the Aztecs
Vargaard: North America
(that should do it

)
This thread got me to thinking about the effects of long term (relatively) low level contact between the lands of Æropa and Vargaard (via Atlantl) on the fantasy world of Ærth (
Dangerous Journeys: Mythus setting). Fret not, I'll restrain myself and not cover the whole of Vargaard. Just the Missourian Tribes.
Which would be the Vargaardian aboriginal tribes living along the Missouri River.
The current year, by Æropean reckoning, is now 1003 since the fall of Atlantl. After close to 3,000 years of contact with Æropa via Atlantl, Vargaard has gone through a few changes. With the introduction of horses, cattle, and grains, the Missourian tribes have made a few changes. Their villages have grown into towns, and some few have expanded into cities. Making the Missourian culture one of the largest in Vargaard in terms of territory and population.
Along with this urbanization has come a breakdown in the tribal structure. Missourians are more apt to refer to themselves as being from a particular town or city than as belonging to a particular tribe or band.
At present the Missourians are organized as a series of city states, but along the upper reaches the expansion of the Nakota is forcing the western plains tribes (Crow, Arapaho, etc.) into Missourian territory. So the Missourian city states along that stretch of the river are starting to cooperate against the raiders/immigrants. At the same time the Comanche are encouraging the Missourians along the lower third of the Missouri River to join together against the growing Teclan threat.
Other than the Nakota, The Sioux (which also includes the Cheyenne, who joined a couple of generations ago) are being good neighbors. But Missourian colonists are establishing towns, and even a few cities, in Lakota and Nakota territory, which is starting to cause some friction. (The Sioux herd bison, and the introduction of Missourian cattle into their grazing lands is causing no end of resentment.)
There you have a snapshot of current conditions on the High Plains of Vargaard. A new civilization aborning, imminent hostilities, and a paradigm shift in an ancient culture.
I could mention the Iroquis and their expansion westward to incorporate the tribes of the Ohio Valley into their "benevolent" association, which is worrying the Dakota no end, and their allies further west. The Sioux are debating the wisdom of a war to drive the Missourians from their land. A concurrent war against the Iroquis over the Ohio Valley could cripple their defense of their Northern Plains holdings. But, that would make this message a tad too long.
Be that as it may, I hope you found this useful in one way or another.